VOL. 76/SEP. 1996 - Mitsubishi Electric

MITSUBISHIELECTRIC

VOL. 76/SEP. 1996

Programmable Logic Controllers Edition

TECHNICAL REPORTS

OVEROVEROVEROVEROVERVIEWVIEWVIEWVIEWVIEWGeneral-Purpose MELSEC Sequencers: Present Capabilitiesand Future Prospects ................................................................................. 1by Keishi Ohbuchi

CONTENTSCONTENTSCONTENTSCONTENTSCONTENTS Editor-in-Chief

Editorial Advisors

Mitsubishi Electric Advance is publishedquarterly (in March, June, September, andDecember) by Mitsubishi Electric Corporation.Copyright © 1996 by Mitsubishi ElectricCorporation; all rights reserved.Printed in Japan.

MELSEC QnA/QnAS Series High-Speed, MultifunctionProgrammable Logic Controllers .............................................................. 2by Shun Ohta and Hideaki Morita

Q4AR High-Performance Redundant Programmable LogicController with Problem-Oriented Language Support ............................ 5by Noboru Sakamoto

Intelligent Positioning Modules for ProgrammableLogic Controllers ........................................................................................ 7by Shun Ohta and Haruhiko Kondo

“MELSEC Medoc Plus” IEC 1131-3-Compliant PLCProgramming Tool ................................................................................... 10by Tatsuhiro Kurashima

GOT 800 Series Graphic Operation Terminals ...................................... 12by Narihiro Akatsuka

The FX-50DU High-Performance ProgrammableDisplay Terminal ....................................................................................... 14by Michiaki Isobe and Takeyoshi Kondo

R&D PROGRESS REPORTA PLC Programming System Based on Block Diagrams ...................... 16by Tsutomu Yoshikawa and Takayuki Nihei

TECHNICAL HIGHLIGHTSThe Application of Concurrent Engineering to the Developmentof Graphic Operation Terminals for ProgrammableLogic Controllers ...................................................................................... 20by Hidemasa Iida and Yasuyuki Suzuki

The Trend Toward Open-System Controllers ........................................ 23by Yoshinori Tsujido

Field Area Network for Factory Automation .......................................... 25by Noriyasu Fukatsu

NEW PRODUCTS ................................................................................. 26

NEW TECHNOLOGIES ........................................................................ 27

NEW PRODUCTS ................................................................................. 28

MITSUBISHI ELECTRIC OVERSEAS NETWORK

Akira Yamamoto

Jozo NagataToshimasa UjiTsuyoshi UesugiSatoru IsodaMasao HatayaGunshiro SuzukiHiroshi ShimomuraHiroaki KawachiAkihiko NaitoNobuo YamamotoShingo MaedaToshikazu SaitaHiroshi TottoriMasaaki Udagawa

Masami Niwa

Masaaki UdagawaPlanning and Administration Dept.Corporate Engineering, Manufacturing &Information SystemsMitsubishi Electric Corporation2-3-3 MarunouchiChiyoda-ku, Tokyo 100, JapanFax 03-3218-2465

Tsuyoshi UesugiStrategic Marketing Dept.Global Operations GroupMitsubishi Electric Corporation2-2-3 MarunouchiChiyoda-ku, Tokyo 100, JapanFax 03-3218-3597

Orders:Four issues: ¥6,000(postage and tax not included)Ohm-sha Co., Ltd.1 Kanda Nishiki-cho 3-chomeChiyoda-ku, Tokyo 101, Japan

Vol. 76 Feature Articles Editor

Editorial Inquiries

Product Inquiries

Programmable Logic Controllers Edition

Centerpiece of our cover is the Q4ARprogrammable logic controller, one of anextensive range of advanced products thatprovide the flexibility and sophisticatedfunctions to act as the “brains” ofmanufacturing systems in the era ofautomated multiple-machine processing.

●Vol. 76/Sep. 1996 Mitsubishi Electric ADVANCE

A Quarterly Survey of New Products, Systems, and Technology

TECHNICAL REPORTS

OVERVIEWGeneral-Purpose MELSEC Sequencers:

Present Capabilities and Future Prospects

Keishi Ohbuchi*

*Keishi Ohbuchi is with the Nagoya Works.

General-purpose sequencers (the name under which Mitsubishi Electric marketsprogrammable logic controllers, i.e., PLCs) have, in the 1990s, come into wide-spread use as critically important elements in many areas of factory automation

(FA) and computer integrated manufacturing (CIM). Thanks to an increasingly sophisti-cated range of functions that include calculation, information processing and network-ing support, they can be found throughout industry controlling manufacturing processes,assembly, inspection and transportation.

Market needs for configuring and optimizing total FA systems impose additionaldemands upon these sequencers for more functional operation and the extension of theirapplication to the control of electric power distribution, building supervision andmanagement, and simple instrumentation installations.

The corporation has responded to these needs with PLCs embodying key advancedtechnologies selected to have the greatest impact on functionality, performance, minia-turization and networking capabilities. They are multifunctional with built-in intelli-gence. Again, ease of use is a key factor in increasing added value, so the corporation hasimplemented revolutionary changes in the environment for software development, atthe same time using dual CPUs to achieve high reliability, ease of maintenance, and toprovide diagnostic functions. These have established a strong leadership position forMitsubishi sequencers. This special edition of Advance introduces trends in productdevelopment for the main product categories and the advanced technologies that maketheir performance possible. ❑

September 1996 · 1

TECHNICAL REPORTS

MELSEC QnA/QnAS Series High-Speed,Multifunction Programmable Logic

Controllers

2 · Mitsubishi Electric ADVANCE

by Shun Ohta and Hideaki Morita*

Fig. 1 QnA Series modules.

MELSEC AnS compact PLCs; other specifica-tions are identical to those of the QnA Series.

FeaturesTable 1 summarizes the specifications of theMELSEC QnA and QnAS series. CPU modulesfor both series use dedicated processors devel-

Programmable logic controllers (PLCs) are play-ing a more important role as the systems theyoperate grow larger and more complex. Today’susers are demanding PLCs with higher perfor-mance, more sophisticated functions, high reli-ability and reduced software development cost.This article reports on the MELSEC QnA seriesof PLCs developed to meet these needs.

BackgroundThe QnA and QnAS series have been designedto improve execution performance and raise theefficiency of user program development. Thiswas achieved by introducing a number of en-hancements to the corporation’s previous PLCproducts:

1. Support for structured programming allowsmultiple designers to work on a single project.

2. Programs can be standardized.3. An efficient, easily learned user interface fol-

lows the model of commercial software pack-ages.

4. Overall performance has been scaled upthrough improvements in the processorunits, data bus and networking interface.

5. Extended program memory and device capac-ity ease program design restrictions.

6. Compact QnAS Series products are availablefor embedded applications.

System ConfigurationFig. 1 shows the basic components of a QnASeries PLC: high-performance CPU modules, 15memory cards (incompliance with the standardsof the Japan Electronic Industry DevelpmentAssociation), network interface modules de-signed to match closely with the CPU modules,a high-speed access CPU base unit that boostsoverall performance and a software package pro-viding total program development support.

The new series maintains backward compat-ibility with existing MELSEC A Series CPU baseunits, power-supply modules, I/O units and mostspecial-function units.

Fig. 2 shows a QnAS CPU module. The formfactor is designed for compatibility with

Fig. 2 A QnAS CPU module.

*Shun Ohta and Hideaki Morita are with the Nagoya Works.

TECHNICAL REPORTS

oped at Mitsubishi Electric for sequence pro-cessing. With an operating speed of 0.075µs, thetop-end CPU module offers double the perfor-mance of its predecessor. There are four CPUmodules for the QnA Series and two for theQnAS Series, allowing processing capability andmemory capacity to be scaled to the applica-tion. The high-speed access CPU module offersdouble the data throughput of previous equip-ment, and the memory cards offer high-speed

Table 1 MELSEC QnA/QnAS Series Programmable ControllersTable 1 MELSEC QnA/QnAS Series Programmable Controllers

Product Part no. Specifications Remarks

CPU modules

Q2ACPU 512 I/O points, 28k steps, 0.2µsQ2ACPU-S1 1,024 I/O points, 60k steps, 0.2µsQ3ACPU 2,048 I/O points, 92k steps, 0.15µsQ4ACPU 4,096 I/O points, 124k steps, 0.075µs

Q2ASCPU 512 I/O points, 28k steps, 0.2µs CompactQ2ASCPU-S1 1,024 I/O points, 60k steps, 0.2µs

High-speed access A38HB Double-speed data bus, other specifications identical to A38B

CPU base units A1S38HB Double-speed data bus, other specifications identical to A1S38B Compact

JEIDA 4 compliant

Q1MEM-64S 64KB

SRAM cards

Q1MEM-128S 128KBQ1MEM-256S 256KBQ1MEM-512S 512KBQ1MEM-1MS 1MBQ1MEM-2MS 2MB

JEIDA 4 compliantQ1MEM-64SE 32KB/32KBQ1MEM-128SE 64KB/64KB

SRAM/EEPROM Q1MEM-256SE 128KB/128KBcards Q1MEM-512SE 256KB/256KB

Q1MEM-1MSE 512KB/512KB

JEIDA 4 compliantQ1MEM-256SF 128KB/128KB

SRAM/flash memoryQ1MEM-512SF 256KB/256KB

cardsQ1MEM-1MSF 512KB/512KBQ1MEM-2MSF 1MB/1MB

Two-strand optical- AJ71QLP21 MELSECNET/10 management station, remote master stationfiber loop networks AJ71QLP25 MELSECNET/10 remote station

Single-conductor AJ71QBR11 MELSECNET/10 management station, remote master stationcoaxial bus networks AJ72QBR15 MELSECNET/10 remote station

Serial communica-AJ71QC24 RS232C (1 channel, D-sub connector), RS422/485 (1 channel, terminal)

tion modulesAJ71QC24-R2 RS232C (2 channels, D-sub connectors)AJ71QC24-R4 RS422/485 (2 channels, D-sub connectors, terminal)

Simple programmingQ6PU Programming module for QnA Series

module

Software packages

SWONX/IVD-GPPQ GPP and SFC functions, program editor, monitor, debuggerSWONX/IVD-LNKQ Ladder sequence program linkerSWONX/IVD-CNVQ Data conversion utilitiesSWONX/IVD-CADQ CAD interfaceSWONX/IVD-MSPQ Macro libraries for special-function modulesSWONX/IVD-MSDQ Macro libraries for standard circuits

access to support realtime control of compli-cated systems.

The QnAS CPU modules are compatible withthe power-supply, I/O and special-function mod-ules of the MELSEC AnS Series. Their specifi-cations are identical to corresponding QnA CPUmodules with the exception that they can ac-commodate only one memory card.

The MELSECNET/10 serial communicationmodule features a dual-port buffer that supports

September 1996 · 3

TECHNICAL REPORTS

reliable high-speed transfers between PLCs andpersonal computers.

The MELSEC QnA and QnAS series softwarepackage supports graphic programming designusing ladders or sequential functional charts andprovides a debugger. Up to four programs can beedited concurrently, with a cut-and-paste func-tion between code windows (Fig. 3).

Support for user-defined macro instructionscontributes to simpler, standardized programs,and allows users to build macro libraries forspecific applications (Fig. 4).

A hierarchical file system supports transpar-ent program management, allowing multipledesigners to collaborate on programming,


Fig. 3 Multiple file editing.

Y110

Cut and pasteB30

LD X0OR Y10

X100 X97

Y110

Y10

K50

T5

Designer B

Designer A

Designer C Assembly

Processing

Receiving

by functionby processby programmer

Faultprocessing

Mainprocessing

Initialprocessing

Fig. 4 A hierarchical file system.

In addition to state-of-the-art hardware, MELSECQnA and QnAS series PLCs incorporate advancedprogramming features that dramatically boostsoftware productivity and facilitate maintenance.With these features, it is possible to meet therealtime control requirements of highly compli-cated systems. ❑

Fig. 5 A macro instruction.

M. Line Test W0 W2

Macro

B0

+ K2 W0

– W0 W2

debugging and maintenance. Program files canbe organized by function, designer, process orother criteria (Fig. 5).

Devices can be specified by labels rather thandevice numbers, which permits standard pro-grams to be easily ported from one installationto another.

TECHNICAL REPORTS

Q4AR High-Performance RedundantProgrammable Logic Controller with

Problem-Oriented Language Supportby Noboru Sakamoto*

*Noboru Sakamoto is with the Nagoya Works.

has symmetrically organized power-supplymodules, CPU modules, system control mod-ules and network interface modules. An auxil-iary base unit is connected via a centrallypositioned bus switching module to allow con-trol of I/O and special-function modules.

The CPU modules have performance andfunctions comparable to the top-end MELSECQ4A CPU. A coprocessor for floating point op-erations performs basic arithmetic four timesfaster than comparable single-processor CPUmodules. The main CPU and backup CPU per-form data tracking via a dedicated bus, and arith-metic results from the main CPU are transferredto the backup CPU so that, if the main CPUgoes down, the backup CPU can continue pro-cessing in the same state.

The system control modules monitor the CPUand power-supply modules. When they detecta fault, they send a switch command to the bus

Trends toward downsizing and open architec-ture in distributed control systems can be seenin the popularity of factory systems imple-mented by networks of personal computers andprogrammable logic controllers (PLCs). This ar-ticle reports on the Q4AR redundant PLC de-signed to meet distributed control requirementswhile providing the high performance and reli-ability needed for “mission critical” factory con-trol applications.

ConfigurationThe Q4AR has a backup processor and backupnetwork interfaces for enhanced reliability, andfeatures a full complement of sequence pro-gramming instructions for problem-orientedlanguages (POLs) including proportional, inte-gral and derivative functions.

Fig. 1 shows the configuration of a Q4AR-based redundant control system. The base unit

Fig. 1 Redundant system construction.

MELSECNET/10 (PLC-to-PLC network) Sub loop

Main loopSystem A System B

Tracking bus

Power-supply

unit

Networkinterface

unit(remote)

Networkinterface

unit(PLC-to-

PLC)

Systemcontrol

unit

Redun-dant

CPU unit

Busswitch-

ingunit

Redun-dant

CPU unit

Systemcontrol

unit

Networkinterface

unit(PLC-to-

PLC)

Networkinterface

unit(remote)

Power-supply

unit

Up to seven auxiliary base units can beconnected. Each auxiliary base unit can have upto two power supplies for redundant operation.

Power-supply

unit

ExistingCPUunit

Networkinterface

unit

I/O unit I/O unitPower-supply

unit

Power-supply

unit

Auxiliary base unit with redundant functions (level 1)

Sub loop

Main loop

Remote I/O network

Networkremote

unit

I/O unitPower-supply

unit

Power-supply

unit

I/O unitNetworkremote

Power-supply

unit

September 1996 · 5

TECHNICAL REPORTS


switching unit and activate a set of relay con-tacts.

The bus switching module links the mainCPU bus to the auxiliary base unit in responseto switch commands.

The network interface modules provide re-dundant MELSECNET/10 compatible inter-faces and a switching function to select betweenthem. The hardware is backward compatible,allowing redundant equipment to be installedin existing networks.

When phenomena satisfying failure criteriaoccur, the backup CPU is switched on to re-place the main CPU. Switching is initiatedautomatically by a power-supply failure, diag-nostic abnormality or network unit failure.Switching can also be initiated manually.

The control and backup CPU perform datatracking over parameter-selected devices. Theprocessing requirements associated with thisfunction are lowered by tracking only activedevices.

The network interface modules in the baseunit periodically check to ensure that the mainCPU is up, and switch to the backup CPU whenthe main CPU goes down.

Diagnostic functions maintain synchronybetween the main and backup CPUs by com-paring parameters and program data. Updatinga program in the main CPU module while thesystem is operating will cause the backup CPUmodule to update the corresponding program.

The Q4AR has a number of special instruc-tions supporting the POLs used in process con-trol applications. POLs enable process controlto be implemented by use of expressions thatcan connect individual function blocks. Theseexpressions are converted to the correspondinginstructions and implemented on the PLC.

Fig. 2 shows an example of a loop-controlapplication using proportional integral deriva-tive (PID) instructions. These instructions ac-complish control using locally availablememory (block memory and parameters) andglobally available memory (loop memory).

The redundant functions of this PLC are be-hind the outstanding reliability it offers for“mission critical” factory control applica-tions. ❑

PROBLEM-ORIENTED LANGUAGE

Fig. 2 Problem-oriented language and sequence operation.

Input PHPL OutputPID

Parameters Blockmemory




Loop memory

SEQUENCE INSTRUCTIONS

Start contacts

Start contacts

Start contacts

Start contacts

Input

S.IN D0 D5 D10 D60

S.IN D15 D20 D25 D60

S.IN D30 D35 D40 D60

S.IN D45 D50 D55 D60

Blockmemory

Blockmemory

Blockmemory

Blockmemory

Loop memoryKeyPHPL Process variable high

process variable lowPID Proportional integral derivative

D10

D25

D40

D55

D60

D5

D20

D35

D50

TECHNICAL REPORTS

Intelligent Positioning Modules forProgrammable Logic Controllers

*Shun Ohta and Haruhiko Kondo are with the Nagoya Works.

by Shun Ohta and Haruhiko Kondo*

Fig. 1 The positioning modules.

a) A1SD75P3 b) AD75P3

September 1996 · 7

ment.Six functions for origin recovery when acti-

vated support a wide variety of applications.Step and S-curve acceleration patterns may

be selected to minimize impacts associated withaxis start and stop operations.

Open collector and differential pulse trainmotor drive interfaces support a wide variety ofmotor drives. The differential interface canoutput pulses at rates up to 400kHz to supporthigh-speed motor control. Table 1 summarizesthe AD75 Series functions and performance.

ProgrammingPositioning statements use the table position-ing scheme of the AD71 Series for backwardcompatibility and easy upgrading.

The AD75 Series has internal parameters con-trolling movement conditions and simulta-neous start conditions for other-axis start,

Factory automation systems are being used tomanage more varied and complicated tasks.Intelligent modules are a key to implementingthese systems because they extend and comple-ment the functions of programmable logic con-trollers (PLCs). Intelligent modules offer suchfunctions as analog-to-digital (AD) and digital-to-analog (DA) conversion, high-speed count-ing, temperature input and positioning control.This article introduces the AD75 Series posi-tioning modules.

DescriptionThe AD75 Series offers dramatic enhancementsover the previous AD71 Series in performance,functionality and versatility. Use of a 32b RISCprocessor with peripheral circuits implementedin custom LSIs gives the series high perfor-mance and compact dimensions. A program-ming software package for the series supportscreation of positioning data, monitoring ofmodule operating status, and other program-ming and maintenance tasks.

LineupThe AD 75 Series offers 1- to 3-axis controlmodules for MELSEC A, QnA and A1S seriesPLCs. All modules consume only a single slot,which contributes to reduced equipment sizeand cost. Fig. 1 shows the A1SD75P3 andAD75P3 three-axis positioning modules.

Functions and PerformanceThree-axis independent control, two-axis lin-ear interpolation, two-axis circular interpola-tion and continuous positioning controlfunctions are supported. These functions canbe combined for continuous positioning con-trol and are thus capable of supporting up to600 points, which supports extremely compli-cated control functions.

External signal inputs for startup and speed-position switching reduce scanning demandson the sequencing program and the associatedresponse delays. The PLC processing time re-quired for positioning control is reduced by 75%compared to previous positioning units, whichleads to shorter tact times for controlled equip-

TECHNICAL REPORTS

which reduces sequence programming require-ments and provides high-precision positioningthat is not dependent on sequence program scantime. Parameter setting is performed using anoptional positioning module software package.

Positioning data is stored in flash memory,eliminating battery-related maintenance re-quirements.

Monitor FunctionsThe module has a 2.5 digit LED display thatcan be used to monitor zero-point signal inputsand mechanical inputs such as near-point dogand upper/lower limits for quicker equipmentinstallation and adjustment. The display alsooutputs error codes to facilitate troubleshoot-ing.

Positioning Module Software PackageThis software package, which operates underthe Mitsubishi Electric A7PHP/A7HGP periph-eral unit or a personal computer, offers edit,monitor and test modes, with simple switch-ing from editing to online monitoring or test-ing. Fig. 2 shows the top-level edit-mode screen,and Fig. 3 the screen for positioning data edit-ing. Positioning data editing is assisted by aux-iliary windows for displaying menus and settingranges.

The test and monitor modes permit detailedmonitoring of the module’s current status andoperation history. The user can select monitor-ing of current feed position and feed speed foreach axis as well as error history, warning his-tory, external I/O signals and the state of the

Parameters\Products AD75P1, A1SD75P1 AD75P2, A1SD75P2 AD75P3, A1SD75P3

I/O points 32

Control capability 1 axis2-axis simultaneous, 3-axis simultaneous,2-axis independent 3-axis independent

Pulse output Open collector, differential driver

Control method Point-to-point control, continuous control (linear or circular), speed control, speed-position control

Interpolation None 2-axis liner/circular interpolation

Positioning Language Table method

Position pattern 600 patterns per axis

Memory Battery-less flash EEPROM program storage

Absolute position limits−214,748,364.8 ~ 214,748,364.7µm, −21,474.83648 ~ 21,474.83647 inches, 0 ~ 359.99999 degrees,−2,147,483,648 ~ 2,147,483,647 pulses

Increment limits −214,748,364.8 ~ 214,748,364.7µm, −21,474.83648 ~ 21,474.83647 inches,−21,474.83648 ~ 21,474.83647 degrees, −2,147,483,648 ~ 2,147,483,647 pulses

Speed instruction range 0.01~ 6,000,000.00mm/min, 0.001~ 600,000in./min, 0.001~ 600,000°/min, 1~ 1,000,000 pulses/s

Acceleration processing Automatic step acceleration, automatic S-curve acceleration

Acceleration time 1.0 ~ 65,535ms, four patterns each for acceleration and deceleration

Startup time Less than 20ms

CompensationElectronic gear 0 ~ 65,535 × position instruction unitBacklash compensation 0 ~ 65,535 × position instruction unitError compensation function Compensates for systematic mechanical errors (includes electronic gear support)

Origin recovery functions Near-point dog, count (2), stopper (3), external signal (2)

Manual operation Supports one manually operated rotary encoder for each axis

Error and I/O display Provided by 2.5 digit LED display

Table 1 Specifications of the AD75 Series Positioning Modules


TECHNICAL REPORTS

September 1996 · 9

positioning module’s internal XY device. Fig. 4shows a typical monitoring screen.

A utility program is provided to convert userprograms developed for AD71 Series modules

Fig. 4 A monitoring screen.

Fig. 3 The position data edit screen.

Fig. 2 The top-level edit-mode screen.

for use under the AD75 Series so as to protectexisting software development investments.The only manual modifications required are theaddition of a few parameter settings where func-tional enhancements have occurred.

Use of these positioning modules and their sup-port software extend the capability of PLCs.They dramatically reduce the time and costrequired to develop sequence programs, and sim-plify equipment installation, setup and main-tenance. ❑

TECHNICAL REPORTS

“MELSEC Medoc Plus” IEC1131-3-Compliant PLC

Programming Tool

*Tatsuhiro Kurashima is with the Nagoya Works

by Tatsuhiro Kurashima*

Mitsubishi Electric has developed program-development software for international use incooperation with MEG, one of the corporation’soverseas sales companies. Called MELSECMedoc Plus, the software offers an environmentthat supports IEC 1131-3 and the corporation’sproprietary language standards.

DescriptionMELSEC Medoc Plus is a programming envi-ronment that operates under Windows 3.1. TheIEC 1131-3-compliant environment supportsfour languages: instruction list (IL), ladder dia-gram (LD), sequential functions chart (SFC) andfunctional block diagram (FBD). It also supportstwo Mitsubishi-developed proprietary languagestandards for IL and LD programming. Functionsand function blocks can be expressed for IEC1131-3.

Most operations are performed via the Win-dows graphic user interface using a mouse, pull-down menus and multiple windows, as withother Windows applications. The software sup-ports dynamic data exchange (DDE), providingdata sharing capabilities that support integra-tion with other software.

Structured Programming and SupportLanguageThe resources (mentioned in Fig. 1) under theconfiguration are supported in MELSEC MedocPlus as one project. The user develops programsin program organization units (POUs), and theexecution conditions are defined for the task.

Configuration

Resource 1 Resource n

Task 1

POU 1

POU n

Task n

Global variables

KeyPOU Program organization unit

Fig. 1 The IEC 1131-3 configuration.

Resource (project)I – – PLC parameterI – – Data unit typeI – – Global variableI – – TaskI – – POU

I – – Local variableI – – Program bodyI – I-ProgramI SFCI ActionI FBD/LD/IL/MELSEC LD/MELSEC ILI TransitionI FBD/LD/IL/MELSEC LD/MELSEC ILI FBD/LD/IL/MELSEC LD/MELSEC ILI – Function blockI FBD/LD/IL/MELSEC LD/MELSEC ILI – FunctionI FBD/LD/IL/MELSEC LD/MELSEC IL

Fig. 3 Function block.

KeyFB Function blockI/O Input/OutputMOV Move instruction

Header: Input variableOutput variableGlobal variableLocal variable

Body:LD Input 1From Input2 K2 Local data K10...MOV Local data Output 2

FB1

I/O No

Buffer No

Read data

Application example

Input 1

Input 2

FB1 Output 2

Fig. 2 Data construction tree.


KeyFBD Function block diagram POU Program organization unitIL Instruction list SFC Sequential functions chartLD Ladder diagram

The POUs, which constitute programs, haveprogram, function block and function associa-tions that support structured programming. Fig.2 shows the data construction tree.

Function Blocks and FunctionsUser programs can be structured and libraries

TECHNICAL REPORTS

developed through the use of function blocksand functions. Fig. 3 shows an example of a func-tion block. MELSEC programmable logic con-troller (PLC) LD and IL languages will supportthese features in the future. All MELSEC in-structions can be registered as MELSEC func-tion blocks. Software reuse can be promoted byregistering frequently used programs (such as aprogram used to access a special-function mod-ule) in a library as a function block.

Easy OperationThe window environment permits concurrentprogram editing and display of parameter dia-log boxes, monitor windows and memory-set-ting dialog boxes. Customized editors for eachlanguage support mouse-based menu selection,cut-and-paste and other Windows environmentfunctions. Fig. 4 shows a typical screen.

Integrated EnvironmentDDE server functions are currently supported,and future support for OLE2 is planned. Theseinter-application communication functionsenable users to create comprehensive environ-ments that unite multiple applications. Thecurrent DDE server functions support two ac-cess modes. One allows access to PLC memoryand program areas. The second allows moni-toring of PLC devices for display and arithmeticpurposes.

This sophisticated PLC programming environ-ment provides excellent support for PLC pro-gram development under the easily used andwell understood Windows graphic user inter-face. ❑

September 1996 · 11

Fig. 4 Typical screen.

TECHNICAL REPORTS

GOT 800 Series GraphicOperation Terminals

by Narihiro Akatsuka*

Mitsubishi Electric has developed five graphicoperation terminals for programmable logic con-troller (PLC) user-interface applications. TheGOT 800 Series helps boost production effi-ciency with advanced functionality, various in-terface capabilities, simple screen design andeasy maintenance.

Product ConceptOperation terminals display the status of I/Opoints and PLC device information as lamps,switch settings, numerical displays, messages,graphs and graphic objects, and support user in-put through a touch screen that allows the op-erator to alter the internal data of the PLC.

The GOT 800 Series is designed to provide acost-effective, full-function electronic PLC con-

Fig. 1 The A870 terminal.

trol panel complete with screen debugging andother maintenance features. The series consists

Fig. 2 The A870 hardware configuration.

*Narihiro Akatsuka is with the Nagoya Works.

MAIN UNIT

Flash ROM

Memory cassetteinterface

Option interface

(for future expansion)

Memory cardinterface

Memory card

Additional memory cassette

32b RISC

System logic(gate array)

DRAM

Display controller

Communicationinterface

Display circuitry(gate array)

RS422

RS232C

RS232C

Font ROM

VRAM

Display peripheralcircuitry

(gate array)

Frame memory

Key logic(gate array)

Touch screen

Buzzer

Bus or network linkwith PC

Serial communicationwith PC

Debugger(for development)

Personal computer forscreen authoring


TECHNICAL REPORTS

Table 2 Maintenance FunctionsTable 2 Maintenance Functions

System monitor

Overall/selected monitoring of CPU devices;set current values of timers, counters andother devices; monitor/modify special-function module buffer memory

Special-function Graphically monitor/modify buffer memorymodule monitor for specific special-function modules

Ladder monitorMonitor ladder program for specified station(with search function); keyword-based PC read/write protection

Table 1 Monitor Functions

Lamp/meter displayLamp images track setting conditions;various meter graphics show numericalvalues

Numerical dataPC device values are displayed in

displaydecimal or hexadecimal notation; usercan specify justification and field width

Comment display Used to display prepared text messages;selected by bit or word data values

Alarm list displayComment display when specified devicebit turns on; message scroll whennumerical data values change

Object display/moveParameter controlled display of graph,text or image objects; objects trackchanges in bit or word values; display ofimage data from external equipment

Trend graph Display of word values as a function ofdisplay time; scrolling supported

Touch key settings

Display of standard keytop graphics oruser bit maps; signal on/off, toggle andmomentary activation; data write; screenchange

Data inputNumerical data input; password-protectedinput option

Table 1 Monitor Functions


text messages, numeric data and graphs in re-sponse to failures, errors or other system events.The user can install any scanned graphic im-ages as background bitmaps or display elements.

The extensive sequence programming previ-ously required to manage screen displays hasbeen all but eliminated by offloading display-related and arithmetic functions to the termi-nal. Unicode support allows a terminal todisplay some 26,000 different characters cover-ing major European and Asian languages.

Debugging FunctionsThe screen design software runs on Windows3.1 or Windows 95 operating systems. It includesPLC emulation functions that allow thoroughdebugging of terminal-to-PLC communicationsettings so that little or no post-installationdebugging is required. System setup time is re-duced dramatically as a result.

Maintenance FunctionsPLC maintenance functions (Table 2) allow theoperator to check PLC program operation whenproblems occur and quickly identify their ori-gin so that downtime is significantly shortened.System monitor functions enable a terminal tomonitor or write to PLC devices without addi-tional equipment. Special-function-modulemonitor functions provide about 250 screens formonitoring and control of special-function mod-ules. Ladder monitor functions allow sequenceprograms to be monitored in ladder format.

By taking over most display and maintenancefunctions, these graphic operation terminalsdramatically simplify the task of applying PLCsto process automation. ❑

of a large-screen model (A870) and a medium-screen model (A850). The A870 features one ofthree screens: a 640 × 400 dot electrolumines-cent monochrome screen, a 640 × 480 dotsupertwist nematic color LCD or a thin-film-transistor color LCD. The A850 is available witheither a 320 × 240 dot monochrome LCD or asupertwist nematic color LCD.

Hardware ConfigurationFig. 2 shows a simplified block diagram of theA870. The A850 is similar, lacking only thememory cassette interface. The main proces-sor, system gate array and internal data busesfor flash ROM and DRAM are all 32 bits wideto support high-speed data access.

The main processor is a high-performance20MHz 32b RISC device. The touch screen pro-vides a 16 × 16 array of cells approximately 5 ×5mm. The terminals can be connected to PLCsin several ways: by a direct bus connection, by aMELSECNET network link or by an RS422 se-rial cable. They operate on 100/200VAC or24VDC power supplies, and are manufacturedto comply with UL and EN international safetystandards.

SoftwareThe terminal software includes a variety ofmonitoring functions (Table 1) and 3D graphicversions of the familiar lamps, meters andswitches of conventional control panels. Alarmfunctions can be easily configured to display

TECHNICAL REPORTS

Type Name

Static Text, line, rectangle, circuit, bit map

Bit device control Lamp, buzzer, flip text, flip image

Word device Numerical value, bar graph, pie chart, XYcontrol graph, text (indirect), image (indirect)

Key functionsTouch key, switch, screen change, modifydata, increment data, decrement data

Other Date/Time

The FX-50DU High-PerformanceProgrammable Display Terminal

by Michiaki Isobe and Takeyoshi Kondo*

*Michiaki Isobe and Takeyoshi Kondo are with the Himeji Works.


Table 2 Screen Objects

LCD displayMonochrome (Model TK) or eight-color(Model TKS) supertwist nematic with320 × 240 dot resolution

Touch keys 16 × 8 cells

Connectivity Connection to PC CPU module or externalcomputer

Data interfaces RS422, RS232C, expansion interface

Screen memory 128KB flash memory, 500 screens max.

Power supply 24VDC

ProtectiveIP65

construction

Dimensions 170 ×130 × 66mm

Table 1 General Specifications

Fig. 1 The FX-50DU programmable displayterminal.

Programmable display terminals for program-mable logic controllers (PLCs) offer control en-gineers an attractive user interface with bothmessage display and touch-screen input capa-bilities. This article introduces the features ofthe FX-50DU programmable display terminal,which is compact, offers a wide range of func-tions and is easy to use.

Basic SpecificationsThe FX-50DU is designed for user interface appli-cations with MELSEC FX and A series PLCs. Table1 lists the basic specifications. The display termi-nal is available with either of two LCD screens:monochrome or eight-color supertwist nematic.A graphics processor supports display of bitmapsand other graphic images. A transparent touchpanel over the LCD screen supports direct screeninput—an intuitive process that allows the userto indicate choices by touching keys displayed onthe screen. The position and size of the keys canbe set to any multiple of the touch-screen’s unitcells.

The display terminal is linked to a PLC by asimple serial cable. All necessary communica-tions support is provided; no additional user soft-ware development is required. Data is exchangedwith the PLC automatically based on the screendata contents.

Screen CreationScreens are created on a personal computer usingspecial-purpose utility software that requires nospecial training to operate. To create a screen, theuser simply places text, bar graphs and other ob-jects on a blank sheet. Systems of up to 500 screenscan be created. Table 2 lists available screen ob-jects. Each object has its own parameter list thatspecifies images, object behavior, links to PLC dataand links to other screens. Table 3 lists the param-eters of a typical numerical object. The object dis-plays numerical data from the PLC.

Bitmap images can include standard BMP filescreated by commercial graphics software. A li-brary of lamps, switches and other commonlyused images is provided to support easy creationof clear and attractive screens.

Once the screens are completed, the correspond-

ing data is transferred to the display terminal viaserial cable. The data is stored in non-volatile flashmemory that requires no battery backup.

TECHNICAL REPORTS

Device Monitor FunctionsThese functions allow the display terminal tomonitor data from timers, counters, I/O and otherPLC devices. The user can select monitoring tar-gets from the display terminal without program-ming, allowing the user to check and adjust PLCdevices directly through the terminal.

Alarm FunctionsManaging of PLC-controlled installations requiresalarms to alert the operator when equipmenttroubles occur and support for later analysis ofevent histories by type and frequency of occur-rence. The display terminal has a full range ofalarm functions that can pop up messages in re-sponse to abnormal conditions. The user links theabnormal condition to a PLC bit device and regis-ters a message in the display unit. The displayunit monitors bit devices. When an ‘on’ is detected,a window pops up with the alarm message, andthe event type and time are logged in a historyfile. The event history data can be viewed on thedisplay terminal, transferred to a personal com-puter for storage and analysis or output directly toa printer.

These functions give users access to a full rangeof event capabilities through simple display ter-minal and PLC bit device settings. Compared todisplay terminals without alarm functions, theprogramming requirements are minimal.

Other FunctionsFor production systems, it may be desirable to

Display position x,y coordinates

Character size Expansion factors for character width, height

Data PC device supplying display data

Digits No. of display digits, including sign anddecimal point

Decimal digits No. of digits to right of decimal point

Format Decimal or hexadecimal display

Modify flagControls permission for alteration by userinput

Upper and lower Allowable input range; values outside thislimits range trigger an error condition

Table 3 Parameters of a Numerical Object


deny routine users access to maintenance screens.The FX-50DU allows screens to be protected witha four-digit code when the screen is created. Oncethis is done, users cannot access the protectedscreen without the code.

The display terminal also has a clock/calendarfunction that that can turn on eight separate PLCbit devices on particular days and times.

The FX-50DU provides an easy-to-use touch-screen graphic interface for PLCs that can be setup with minimal programming. By handling eventmonitoring and logging, the display terminal canmanage most routine PLC operation and mainte-nance requirements. ❑

R&D PROGRESS REPORT

*Tsutomu Yoshikawa is with the Industrial Electronics & Systems Laboratory and Takayuki Nihei with the NagoyaWorks.

R & D PROGRESS REPORT

A PLC Program-ming SystemBased on BlockDiagramsby Tsutomu Yoshikawa andTakayuki Nihei*

KeyFA Factory automationSFC Sequential function chart

Personal computer (Windows NT)

Z=1

Kx

K

++

Monitoring

Trend graphs

Download

Parameter tuning

Ethernet, RS232C

QnA

Process control Discrete event control

Block program Ladder

SFC

FA equipment

Measurement systems

Fig. 1 Block programming system concept.

Block programming system

Ethernet

Download/upload/monitoring/etc.

RS232C (RS-422)

BP


Fig. 2 A program editing screen.

Inexpensive and reliable, programmablelogic controllers (PLCs) are finding applica-tions in measurement as well as factory auto-mation. However, ladder diagrams (LDs), theprincipal language for PLCs, are based on relaycircuits and are inappropriate for process con-trol applications. This article introduces a PLCprogramming method based on block dia-grams, the primary tool for process controldesign.

Block diagrams express control element blocksas transfer variables and describe control sys-tems as series, parallel and feedback relation-ships among these variables. The authors havedeveloped a PLC programming environmentcalled a “block programming system” thatsupports PLC programming and monitoringbased on block diagrams.

The system provides a PLC programmingenvironment that supports the entire processcontrol program development cycle from pro-gram coding to downloading, monitoring andparameter tuning. Fig. 1 illustrates the systemconcept. The system implements a program-ming language based on graphical representa-tions of block diagrams. The high-level natureof the language permits efficient programdevelopment. The graphical program listingsare highly legible, providing excellent docu-mentation of the program’s operation. Fig. 2shows a typical program editing screen.

System ConfigurationFig. 3 shows the system configuration. Thesystem runs on a personal computer linked to aPLC via a network or serial cable, and can beused to create programs, download them to thePLC, upload them from the PLC and monitorPLC program execution. The completed pro-grams are stored in PLCs in the same way as Fig. 3 A system configuration.

R&D PROGRESS REPORT

Fig. 4 The software module configuration.

Visual programming framework

Blockprogrammingsubsystem

LD subsystem SFC subsystem

Visual programming class library

Project manager

Objectdatabase

GUIservice

Online

MonitoringTrendsParameter tuning

Translators

Block, LD or SFCto execution code

Communications port(s)/EthernetWindows

KeyGUI Graphic user interfaceLD Ladder diagramSFC Sequential function chart

ladder programs, which simplifies field main-tenance.

The software modules of the block program-ming system are shown in Fig.4. The integratedenvironment for program editing and monitor-ing embodies both a visual programming classlibrary that expresses the blocks—and the con-necting links between them—used in blockdiagrams, and a visual programming frameworkthat supports unified project managementacross a number of programming languages.This makes it possible to handle LD, sequen-tial function chart (SFC) and other distributedcontrol languages in the same way as theblock programming system, written in theprocess control language.

The portability of the block programmingsystem is improved by modularization of datamanagement functions and display functions.This is implemented as an object database andgraphic user interface (GUI) service. The objectdatabase provides for management of basicdata types and structures and for basic objecthandling. Unified management is provided forall internal objects containing protected datain terms of fundamental classes. The GUIservice conceals the complexities of the Win-dows application programming interface (API),providing a simpler API that facilitates userinput operations and graphic displays.

Specialized translator modules have beenprepared for all machines on which the pro-grams will be implemented so as to provideonline functions for monitoring or parametertuning by generating execution code from theblock programming language.

Programming MethodThe programming language consists of blocks Fig. 5 The development process.

Operation

Debug using monitoring or parameter tuning

Execution on PLC

Download

Executablecode

LibraryCode generation

Program coding

Control program design


representing I/O, linear and nonlinear arith-metic, programming interface diagram (PID)control and other functions. The language hasenhancements that support I/O statementscontrolling PLC relay circuits, special-functionmodules and data sharing with ladder pro-grams. Fig. 5 shows the steps involved in cre-ating programs. A graphical editor is used togenerate and edit programs. The mouse is usedto select blocks from menus, place them onthe screen and interconnect them. Table 1 liststhe standard blocks supported by the systemand their parameters. Associations for eachblock are set using dialog boxes.

Programs are created in units of projects, asingle project defined as all the code executedby a single PLC. A project consists of threeelements: a program, which corresponds to acontrol loop; blocks, the smallest programunits; and tasks, the units of execution.

One project can be implemented as severalprograms, each of which may contain severalsubprograms creating a hierarchical structure.Program associations describe execution inter-vals, limitations and parameters. Tasks can bedesigned independently from programs inblock units, and in units of periodic execution.

R&D PROGRESS REPORT

devices are allocated. Finally, links to libraryroutines are processed to create executablecode.

The executable code is uploaded to the PLCas a single program that is executed periodi-cally. Block programs executed on a MELSECQ4A PLC can be used in up to eight loops (onePID/loop) with periods of 100~200ms, which issufficient for simple measurement applica-tions.

Block programs can be executed alongsideladder programs developed for discrete eventcontrol. Block programs can also be executedin sync with ladder programs, or asynchro-nously in open CPU time slices. Data can bepassed between ladder and block programsduring synchronous execution using load andstore blocks, and ladder programs can be usedto specify block parameters. This allows pa-

Code Generation and ExecutionA translator converts the control program intoexecutable, discrete-event control code in threesteps. First, scheduling generated from theblock link and association data is used todetermine the execution order. Next, memory

Table 1 Standard Blocks

Type Block name Function Param0 Param1 Param2 Param3

I/O

LOAD Load internal register Device name

STORE Store internal register Device name

INPUT External input (AD) Unit no. Buffer address Channel Scale

OUTPUT External output (DA) Unit no. Buffer address Switch device Scale

COUNTExternal input

Unit no. Buffer address(high-speed counter)

Linear

ADD Addition

SUB Subtraction

GAIN Gain K

AVERAGE Moving average n

DIFFERENTIAL Differential Kd

INTEGRAL Integral Ti

Nonlinear

MUL Multiply

DIV Divide

ABSOLUTE Absolute value

RATE LIMIT Limit variation rate Rise Fall

SATURATION Output value limit Lower Upper

DEAD ZONE Output suppress interval Start End

PATTERN Pattern n Vector

ControlPI PI control Kp Ti

PID CONTROL PID control Kp Ti Td

Other

A CONTACT Contact set A Bit device

B CONTACT Contact set B Bit device

C CONTACT Option Bit device

CONSTANT Constant value C

DELAY Delay element n

FUNCTION Function Type Interval Amplitude

MODULE Subblock

Note: PI, programming interface; PID, programming interface diagram

Table 1 Standard Blocks

Fig. 6 Program structure.

Project

Task 1 Task 2 Task 3 Task n

Block

B1 B3

B4

B2

B5

Program n

Program 2

Program 1


R&D PROGRESS REPORT

rameter settings to be modified on the basis ofPLC type or other site-specific criteria.

Monitoring and Parameter TuningThe program debugging environment employsthe same block diagrams used in program gen-eration and editing. A double click on a blocklink while in the online mode will initiatemonitoring, while a double click on a blockwill initiate parameter tuning.

The monitoring functions can display blockI/O data for any specified link. This data canbe displayed as a trend graph as well as in nu-merical form. The parameter tuning functionsallow alteration of block parameters duringprogram operation.

The online mode detects error conditionssuch as PLC abnormalities and arithmeticoverflow conditions and displays the blockresponsible for the error.

By providing a visual programming languageand monitoring functions, the block program-ming system speeds PLC program develop-ment. Support for interfacing with ladderprograms makes it possible to develop systemsthat mix discrete event control with processcontrol. ❑


TECHNICAL HIGHLIGHTS


*Hidemasa Iida & Yasuyuki Suzuki are with the Nagoya Works.

The Application of Concurrent Engineeringto the Development of Graphic Operation

Terminals for ProgrammableLogic Controllers

by Hidemasa Iida & Yasuyuki Suzuki*

Mitsubishi Electric is nowutilizing a concurrent engineeringmethod in the development ofgraphic operation terminals for pro-grammable logic controllers (PLCs).Incorporating tools for rapidprototyping, circuit and thermalanalyses and an automatic printedcircuitboard (PCB) router, develop-ment time for the A850 graphicoperation terminal (Fig. 1) was re-duced 40% compared to the esti-mated development time requiredusing conventional procedures.

BackgroundConventional hardware develop-

ment proceeds by a “waterfall” pro-cess in which each phase follows,and is dependent upon, its prede-cessor. Upstream changes are ex-pensive because each successive

phase requires perfect data from theprevious process. As a result: Eachphase of development is long be-cause near-perfect results are re-quired; ASIC and PCB reworking is

DEVELOPMENT FLOW

Studies, analysis, concept design

Method design, system design

Detailed design

Production

The tools used this time for the

movement to “round-trip” type.

Method design, system design

Basic hardware design

ASIC designCircuit analysis

PCBcircuitdesign Auto-

maticrouting

Sof

twar

e de

velo

pmen

t

Rapid prototyping

Thermal analysis

Circuit analysis

ASICproduc-

tion

PCBmounting

design

PCB production

System evaluation

Fig. 2 A round-trip concurrent development method.

Fig. 1 The A850 graphic operation terminal developed by concurrent engineering.



frequently required because quali-fication is possible only aftersamples have been manufactured;and software development is de-layed because it must wait for ASICand PCB qualification.

DescriptionFig. 2 illustrates a concurrent engi-neering method that addresses theseshortcomings. The rapid prototyp-ing tool allows functional qualifi-cation of ASICs and PCBs insoftware right up until hardwareproduction. The circuit analysis toolsimulates PCB characteristics, andconflicts can be easily solvedthrough use of the automatic rout-ing tool.

Fig. 3 shows the design flow ofthe rapid prototyping tool (APTIXCorporation) we used. The tooltakes the product netlist (wiringdata) from a workstation and cre-ates the PCB wiring. The tool canembed ASIC and field program-mable gate array (FPGA) emulatorsallowing functional qualification ofthe entire system.

While the rapid prototyping toolchecks system functionality, thecircuit analysis tool determinessuitability of component mountinglocations and circuit patterns interms of crosstalk, reflections andother electromagnetic consider-ations. It performs hardware simula-tion to evaluate circuit characteristics

and performance prior to PCB fabri-cation. Results can then be fed backto the automatic routing tool inrealtime and used to correct theprinted circuit patterns. Thermalsimulations are also performed insoftware to identify potential powerdissipation problems. Power-supplyproblems, in particular, can besolved prior to fabrication, eliminat-ing a prototype production stage.

Fig. 4 compares the product de-velopment times using the tradi-tional waterfall method and the newconcurrent method. The latter re-duces development time by approxi-mately 40%.

Fig. 3 Rapid prototyping tools and their design flow.

ASIC design

Netlist conversion

FPGAconversion

ASIC netlist

FPGA data

ASIC production

Function design (system design)

Hardware design

APTIX system setup

System level qualification (including software)

PCB production

Hardware evaluation

APTIX data generation

Wiring data

Software debugging

PCB design Software design



Use of the concurrent engineeringapproach in the development ofelectronic products offers a more ef-ficient way to develop program-mable controllers and peripheralsthat meet customer needs for func-tionality, while dramatically reduc-ing the time required for productsto reach the market. ❑

Conventional waterfall development: 10 months

WaitingPCB designPCB

production

ASICproduction

ASIC designHardwaredesign

Methodand

systemdesign

Rework

Sample design

Hardwareevaluation

Rework Rework

Softwareevaluation

ReworkWaiting

Sample production

Concurrent development: 6 months

Qua

lifi-

catio

n PCBproduction

Prototype

PCBdesign

Har

dwar

e ev

alua

tion

Com

preh

ensi

ve e

valu

atio

n

Methodand

systemdesign

Hardwaredesign

FPGA ASICemulator

▲

ASIC design

ASICproduction

Prototyping

Sampleproduction

Software design SI SE SEKeyFPGA Field programmable gate arrayPCB Printed circuit boardSE Software evaluationSI Software investigation

▼

▼

▼

▼

▼▼

Four months savings

Fig. 4 Comparison of development periods for the A850 graphic operation terminal.


Compre-hensive

evaluation


The Trend Toward Open-System Controllers

by Yoshinori Tsujido*

*Yoshinori Tsujido is with the Industrial Electronics & Systems Laboratory.

Multifunction controllers that blurthe distinction between sequenceand motion processing are beingimplemented on personal computerplatforms. This article reports ontrends, features and developmentthemes in these open-system con-trollers and covers personal com-puter-based programmable logiccontrollers (PLCs) and computer-ized numerical controllers (CNCs).

BackgroundMultifunction controllers combin-ing sequence control and numeri-cal control functions have recentlyappeared on the market. They arefrequently implemented on per-sonal computer platforms, whichhas become possible due to advancesin microprocessors, peripherals,operating systems and software. Per-sonal computer-based PLCs andCNCs are also growing popular.

Personal computer platforms pro-vide access to abundant softwareresources, and products developedfor non-proprietary hardware havea huge market potential. Personalcomputer-based products can com-bine sequence control with motioncontrol and integrate process con-trol functions with office softwareapplications.

Fig. 1 lists types of conventionaland personal computer-based con-trollers. [Type 1 is a conventionalPLC.] Types 2, 3 and 4 all utilizepersonal computers to provide theuser interface, with advantages ofease of use and uniform behavior.Type 2 utilizes a personal computeronly to provide a user interface. Thepersonal computer in Type 3 utilizesan auxiliary processor to execute thecontrol software. Type 4 utilizes asimple interface with all controlfunctions implemented in software

on the personal computer. Type 4offers maximum flexibility; types 2and 3 offer some flexibility withoutsacrificing reliability.

Software PLCsThe functions of a PLC can beimplemented as a personal com-puter software application. Al-though it lacks the speed of adedicated processor, this approachoffers several advantages: There areboth interpreted and compiled PLCapplications available to suit vari-ous flexibility and speed require-ments. The software configurationgenerally resembles that of Type 4,but some features of types 2 and 3may also be present. Most productssupport IEC1131-3 compliant se-quential function chart (SFC) andladder programming, and some sup-port programming by flow chart.Several personal computer imple-mentations of problem-oriented lan-guages have been proposed.

Personal Computer-Based CNCsPersonal computer-based numericalcontrol applications have beenimplemented using the Type 3model. Type 4 implementationshave been announced, but theirrange of application is limited sincethey cannot provide the millisec-ond-order interrupt response re-quired for high-precision numericalcontrol. Future products are likelyto be Type 3 or Type 2 implementa-tions, with an auxiliary processorproviding reliable realtime perfor-mance. They will be implementedas plug-in cards with interfaces to avariety of personal computers.

Multifunction ControllersMany equipment developers areincorporating CNC functions insoftware-based PLC applications.For example, some software-basedPLC products embed the elementsof motion control language withinSFC language. A key considerationis coordinating multifunction con-

Personalcomputer

Auxiliaryprocessor

Interface

Externalcontroller

Type 2Type 1(conventional

controller)

Controlsoftware

User interfacesoftware

I/O scanner

User interfacesoftware, etc.

Communicationinterface

Controlsoftware

I/O scanner

DeviceDeviceDevice Device

Type 3



Controlsoftware

I/O scanner I/O scanner

Controlsoftware


Fig. 1 Conventional controller and personal computer-based controllers.

Type 4


trollers in various distributed con-trol applications.

Integrated Development andOperation EnvironmentSome development and operationenvironments are implemented asa single application, but more com-mon are multiple applications thatcommunicate with each other—this is seen as the dominant futuredirection. Use of a de facto applica-tion interface standard allows com-patibility between office softwareand third party applications.

Simulation-Based SystemDevelopmentPersonal computers offer possibili-ties for a simulation-based develop-ment environment. This supportsstepwise development by allowingyet undeveloped components to bepartially simulated. Personal com-puters can also support various vi-sualization tools.

Personal Computer ControllerIssuesControllers based on personal com-puters offer user interface advan-tages and the ability to integrate avariety of software tools, however,there are several disadvantages. Thegreatest issue is reliability. Personalcomputers designed for office envi-ronments tolerate only a narrowrange of temperatures. While hard-ware failure in an office might re-sult in the loss of individual datafiles, a similar failure in a factorycould result in more severe damageto machines or human life. More-over, personal computers are not de-signed for realtime applications andcannot guarantee the millisecond-order interrupt response needed forprecise, high-speed control applica-tions. Despite these problems, per-sonal computer-based controllers

are highly attractive in a variety ofsettings, and most reliability andperformance issues can be resolvedby a hybrid approach combining per-sonal computers with some ele-ments of dedicated controllertechnology.

The increasing performance of per-sonal computers makes them an at-tractive platform for implementingPLC and CNC functions. ❑



Field Area Network for Factory Automation

by Noriyasu Fukatsu*

*Noriyasu Fukatsu is with the Nagoya Works.

Demand is growing for field areanetworks that are “flat,” meaningthat users need not be aware of thephysical layers involved, and “seam-less” in that they are capable of op-erating in a multivendorenvironment. This report describesa field area network for MELSEC ASeries programmable logic control-lers (PLCs) that meets system re-quirements for multivendorcompatibility with enhanced userconvenience.

ConfigurationFig. 1 shows the network configu-ration. It consists of a master PLClinked by twisted-pair cable to de-vices such as remote I/O, analog-to-digital conversion modules,high-speed counting modules, in-verters and servos; remote terminalswith an RS232C interface; and in-telligent devices such as operationterminals.

The user can control a variety offield devices from the master PLCI/O relays and registers as if theywere local devices. Intelligent de-vices can access PLC data and pro-grams, and monitor the state of avariety of field devices. The networkalso supports communication withthe RS232C interfaces of personalcomputers, and with printers andmeasuring instruments.

SpecificationsThe MELSEC A Series field areanetwork features improved basictransmission performance,with cy-clic bit and word transfer abilitiesenabling remote I/O, high-speedcounters, inverters and other remotedevices that perform data control tobe easily controlled through the re-lays and registers of the master PLC.Table 1 lists the basic specifications.


Transmission 10Mbps, 5Mbps, 2.5Mbps,speeds 625Kbps, 156Kbps

TransmissionRS485 busmedium

Transfer format HDLC compliant

Max. total length

100m for 10Mbps, 200m for5Mbps, 500m for 2.5Mbps,800m for 625Kbps and 1,200mfor 156Kbps

Error correctionCRCcode

Maximum links 2,048 binary I/O points, 256 word-linked register points

Master PLC Local PLC

Shielded twisted-pair cable

RemoteI/O

Input modulesOutput modulesMixed I/O modules

Intelligentdevices

RS232C interface

Personalcomputers

ModemsPrinters

Instrumentation

Operation terminal

Remote device

ADC moduleDAC moduleTemperature input modulesTemperature control modulesHigh-speed counter modulesInvertersServos

KeyADC Analog-to-digital converterDAC Digital-to-analog converter

Fig. 1 System configuration.


Additional versatility is provided byan automatic refresh function formaster PLC relays and registers, andspecial data access functions thatallow easy data access and controlof field devices.

Open ArchitectureWe developed three custom com-munications protocol LSIs so thatthe MELSEC A Series field area net-work can support multivendor openarchitecture environments. The bitcommunications LSI supports bitdevices for I/O control and opera-tion, and can communicate directlywith the PLC without microproces-sor intervention. The data commu-

nications LSI supports communi-cation between the PLC and devicesthat handle speed or position datafor inverters or servos without ex-plicit communications program-ming. The message LSI supportscommunications between the PLCand operations terminals or otherintelligent devices. It supportsthe numerous communicationtopologies required by distributedsystems. By supporting industrystandard interfaces and providing avariety of support software, the net-work provides easy connectivity tomany kinds of devices.

The outstanding performance, ad-vanced functionality andmultivendor compatibility of theMELSEC A Series field area networkoffer a significant step forward inuser-friendly connectivity optionsfor programmable logic control-lers. ❑


NEW PRODUCTS

MELSECNET Interface Board for IBM-Compatible Personal Computers

applications.The mounting area for FXOS Series

PLCs has been reduced to 65~70%of the FXO Series through the use ofchip components and double-sidedsurface mounting technology. The800-step program storage area isimplemented in EEPROM to allowmaintenance-free, battery-free opera-tion. Since the programming lan-guage is consistent with FX SeriesPLCs, programs can be developedusing efficient development tools forFX Series PLCs.

Ten, 14, 20 or 30 I/O point modelsare available with AC or DC powersupplies, and transistor or relay out-puts. Two AC input models are alsoavailable.

The FXOS Series is manufactured atan ISO9001-certified productionfacility, is licensed with UL standardsand is certified by the National Asso-ciation of Certification Bodies (CE). ❑

Mitsubishi Electric has developedFXOS Series micro programmablelogic controllers (PLCs), the world’ssmallest PLCs and successors to thehighly regarded FXO Series. We firstdeveloped micro PLCs in 1981 forincorporation into electronic relaycontrol boards, and cumulative pro-duction exceeds two million units.The new series provides the perfor-mance and functional enhancementsneeded to manage current technol-ogy, and the more compact dimen-sions demanded for small form-factor

A MELSECNET II interface board.

PLCs without a special access proto-col. The interrupt and I/O port ad-dresses can be configured forcompatibility with other add-in cards.The interface board appears as alocal station under MELSECNET IIand as a normal station underMELSECNET/10. ❑

interface board supports theMELSECNET II optical fiber loop,MELSECNET/10 optical fiber loopand coaxial bus networks. Softwaredrivers and data-link variable supportare provided for MS-DOS, Windows3.1 and Windows NT operating sys-tems. Application development issimple since the user can access

The current trend toward open sys-tems is affecting the factory automa-tion field, leading to a fusion of infor-mation and control systems. Most ofthe next generation of factory sys-tems will shift from PLC-based lay-ered models to new models withPLC-based control and central infor-mation processing at each level, andonly essential information being ex-ported to information processingsystems. Future systems are likely tobe “flat” models employing closelytied PLCs and personal computersdesigned to support direct linksbetween information applications andcontrol system data. A key designissue is achieving this capability whilemaintaining realtime response in thecontrol system.

Mitsubishi Electric has developedan interface board and software forIBM-compatible personal computersthat links them to the corporation’sMELSECNET PLC network products.The software includes data-link vari-ables and drivers, and middleware.The design supports flat systemswith a guaranteed realtime responseof several tens of milliseconds with-out concern for data volume or num-ber of connected PLCs. The short


FXOS Series Ultracompact Programmable Logic Controllers

The ultracompact FXOS Series.

NEW TECHNOLOGIES

Virtual Manufacturing and Computer-Aided Production Engineering

A variety of tools have been devel-oped to lower the cost and speed thedevelopment of manufacturing sys-tems: petri networks are used forproduction flow design and qualifica-tion, CAD systems for facility design,robot simulators for offline teaching,and programming tools for creatingequipment control programs. How-ever, lack of interoperability amongthese design processes limits theversatility of the development envi-ronment.

Production engineering using avirtual factory provides an alternativeapproach. A virtual factory modelsthe physical characteristics of theproduction equipment in three di-mensions, models the productionequipment control logic and usesthese models to simulate a function-ing factory. The main advantage ofthe virtual factory over previous de-velopment support environments isuse of a single integrated model (Fig.1). This reduces the data input op-erations otherwise associated withthe use of each tool, reduces errorsdue to data incompatibilities andsupports concurrent engineeringprocesses where provisional resultsof one operation are available forother purposes.

The virtual factory can be used todetermine productivity, select equip-ment locations and verify correctfunctioning of each station. The modelcan also be used to supply the fac-tory operation data required to de-velop monitoring systems.

Fig. 2 shows a simple factory con-sisting of three conveyers, a robot, amachining center, an automatedstorage/retrieval system and twotransport machines. This system canbe readily modeled as a virtual fac-tory. Objects corresponding to therobot, machining center and otherequipment are chosen from theequipment library and placed on thevirtual factory floor. Operation logic isthen created to describe work flow,and operations of the robot, machin-

Facility design

Fig. 3 A mirrored engineering environment.

Cell control simulator

Equipment simulator Equipment simulator Equipment simulator

RobotMachining center

Devicesimulator

Devicesimulator

Motor Sensor

Cell controller

Real Factory

Machining center RobotMotor Sensor

Program-mablelogiccontroller

Virtual Factory


Fig. 2 A virtual factory

Paper

Control logicdesign

Controlprogramming

Applicationprogramming

DataDataData Data

Facility design Control logicdesign

Controlprogramming

Applicationprogramming

Factory model data

Fig. 1 An engineering system using the factory model.

ing center and other equipment. Wecan then use this logic to simulatefactory operation and evaluate pro-ductivity. The same logic data canalso be used to generate the controlprograms required for the physicalfactory.

The virtual factory model need notserve only as a stand-alone simulator:it can also be an integral part of thefactory system. Engineers atMitsubishi Electric are now exploringa unified environment concept in

which a single control algorithm isused to control both the virtual andactual factory equipment. Modifica-tions to the control logic and factoryequipment would be tested in soft-ware prior to implementing changeson the factory floor. As the quality ofthe virtual factory model improves, itbecomes a mirror image of the physi-cal factory, providing a developmentenvironment that bridges the gapbetween design and implementa-tion. ❑

NEW PRODUCTS

Mitsubishi apricot FT8000 Series Servers

The mounting configuration of Model 400 components.

Parameter Designation Model 400 Model 800

CPUType Pentium Pro 200MHz

Number 1/2/4 8Cache 1st level 16kB, 2nd level 256kB

System cache — 4MB

Memory ROM 512kB

Main memory 32kB-1GB[512]1 256MB-1GBVideo RAM 2MB

Storage

FDD 3.5inch (1.44MB/720kB)

HDD 2GB/4GB (Maximum 228GB[22GB]1) 8GM (Maximum 228GB)

RAID RAID-5 (Option)Others 4 x CD-ROM, 4GB Streaming Tape (Option)

Display monitor 15-inch monitor (Option)

Keyboard 106 keyboard (Option)

Mouse PS/2 type, 2 buttons (Option)

RS-232C1 port: D-sub 9 pin, ASYNC

SMC port: D-sub 25 pin, ASYNC

InterfacePrinter 1 port: Centronics, D-sub 25 pin

Display Analog Interface, D-sub shrink 15 pinKeyboard Mini-DIN, 6 pin

Mouse Mini-DIN 6 pin

I/O Slots PCIx2, PCI/EISAx 5[3]1, EISAx 3[1]1

Server management Server mangement controller (SMC)Regulation VCCI-I

PowerAC input 100V AC, 50/60MHz

supply Power 1 CPU:850W, 2/4 CPU: 900 W, 8 CPU:1, 280W (Maximum)

UPSs Integrated UPS (5 min. at maximum configuration)Environment 10~35°C, 20~80% RH

Dimensions (mm) 450 x 830 x 700 (W x H x D)

Operating Systems Windows NT Server, UnixWare

Note 1: Single CPU modelPentium is a registered trademark of Intel Corporation.Windows NT is a registered trademark of Microsoft Corporation.UixWare is a trademark of SCO.

An apricot FT8000 server.

Specifications of the apricot FT8000

The apricot FT8000 servers offer ahigh-performance, high-reliabilityopen-architecture platform designedto support growth in network-centriccomputing, client-server systems andincreased data processing loads.

The top-end Model 800 featureseight 200MHz Pentium® Pro proces-sors and a 4MB cache. Model 400carries four of these processors. Themain system bus transfers data at528MB/s with error correction codeor parity protection for data integrity.Two 132MB/s peripheral componentinterconnect buses are also pro-vided.

The servers feature a symmetricalmultiprocessor (SMP) bridge LSIchipset developed to implement athird-level cache for a layered bus.The chipset consists of four devicesof three different types with a total ofsome 400,000 gates. Model 800employs two CPU boards each carry-ing an SMP bridge, four processorsand third-level cache.

RAID and fast-wide SCSI control-lers offer a variety of highly reliablehigh-capacity magnetic storageoptions. Up to 228GB of storage issupported using an external cabinet.A RAID5 algorithm executing ondedicated hardware dramaticallyreduces the load on the CPU boardand enhances reliability. Hot-diskswaps are supported with post-replacement data reconstruction.

Modular power supplies are fittedto suit the server configuration, andredundant modules can be installedso that the system is not compro-mised by failure of a single module.Faulty modules can be replacedwithout taking the system offline.

Internal support for an uninter-ruptible power supply eliminates theuse of cables and serial ports thatwould otherwise impact expansion.

A server monitoring and controlunit is provided in the standard con-figuration. The unit displays the


server operation status, monitorsenvironmental conditions, automati-cally reports faults and has log func-tions. It also supports remote power

switching and remote booting, alongwith other functions that provide totaloperation, fault management andsecurity capabilities. ❑

Country Address TelephoneU.S.A. Mitsubishi Electric America, Inc. 5665 Plaza Drive, P.O. Box 6007, Cypress, California 90630-0007 714-220-2500

Mitsubishi Electronics America, Inc. 5665 Plaza Drive, P.O. Box 6007, Cypress, California 90630-0007 714-220-2500Mitsubishi Consumer Electronics America, Inc. 2001 E. Carnegie Avenue, Santa Ana, California 92705 714-261-3200Mitsubishi Semiconductor America, Inc. Three Diamond Lane, Durham, North Carolina 27704 919-479-3333Horizon Research, Inc. 1432 Main Street, Waltham, Massachusetts 02154 617-466-8300Mitsubishi Electric Power Products Inc. Thorn Hill Industrial Park, 512 Keystone Drive, Warrendale, Pennsylvania 15086 412-772-2555Mitsubishi Electric Manufacturing Cincinnati, Inc. 4773 Bethany Road, Mason, Ohio 45040 513-398-2220Astronet Corporation 37 Skyline Drive, Suite 4100, Lake Mary, Florida 32746-6214 407-333-4900Powerex, Inc. Hills Street, Youngwood, Pennsylvania 15697 412-925-7272Mitsubishi Electric Research Laboratories, Inc. 201 Broadway, Cambridge, Massachusetts 02139 617-621-7500

Canada Mitsubishi Electric Sales Canada Inc. 4299 14th Avenue, Markham, Ontario L3R 0J2 905-475-7728Mitsubishi Electronics Industries Canada Inc. 1000 Wye Valley Road, Midland, Ontario L4R 4L8 705-526-7871

Mexico Melco de Mexico S.A. de C.V. Mariano Escobedo No. 69, Tlalnepantla, Edo. de Mexico 5-565-6269

Brazil MELCO do Brazil, Com. e Rep. Ltda. Av. Rio Branco, 123, a 1507, 20040, Rio de Janeiro 21-221-8343MELCO-TEC Rep. Com. e Assessoria Tecnica Ltda. Av. Rio Branco, 123, a 1507, 20040, Rio de Janeiro 21-221-8343

Argentina MELCO Argentina S.R.L. Florida 890-20º-Piso, C.P. 1005, Buenos Aires 1-312-6982

Colombia MELCO de Colombia Ltda. Calle 35 No. 7-25, Oficinas No. 1201/02, Edificio, Caxdac, Apartado Aereo 1-287-927729653, Bogotá

U.K. Mitsubishi Electric U.K. Ltd. Travellers Lane, Hatfield, Herts. AL10 8XB, England 1707-276100Apricot Computers Ltd. 3500 Parkside, Birmingham Business Park, Birmingham, B37 7YS, England 21-717-7171Mitsubishi Electric Europe Coordination Center Centre Point (18th Floor), 103 New Oxford Street, London, WC1A 1EB 71-379-7160

France Mitsubishi Electric France S.A. 55, Avenue de Colmar, 92563, Rueil Malmaison Cedex 1-47-08-78-00

Netherlands Mitsubishi Electric Netherlands B.V. 3rd Floor, Parnassustoren, Locatellikade 1, 1076 AZ, Amsterdam 20-6790094

Germany Mitsubishi Electric Europe GmbH Gothaer Strasse 8, 40880 Ratingen 2102-4860Mitsubishi Semiconductor Europe GmbH Konrad Zuse Strasse 1, 52477 Alsdorf 2404-990

Spain MELCO Iberica S.A. Barcelona Office Polígono Industrial “Can Magi”, Calle Joan Buscallà 2-4, Apartado de Correos 3-589-3900420, 08190 Sant Cugat del Vallés, Barcelona

Italy Mitsubishi Electric Europe GmbH, Milano Office Centro Direzionale Colleoni, Palazzo Perseo-Ingresso 2, Via Paracelso 12, 39-6053120041 Agrate Brianza, Milano

China Shanghai Mitsubishi Elevator Co., Ltd. 811 Jiang Chuan Rd., Minhang, Shanghai 21-4303030

Hong Kong Mitsubishi Electric (H.K.) Ltd. 41st Floor, Manulife Tower, 169 Electric Road, North Point 510-0555Ryoden Holdings Ltd. 10th Floor, Manulife Tower, 169 Electric Road, North Point 887-8870Ryoden Merchandising Co., Ltd. 32nd Floor, Manulife Tower, 169 Electric Road, North Point 510-0777

Korea KEFICO Corporation 410, Dangjung-Dong, K unpo, Kyunggi-Do 343-51-1403

Taiwan MELCO Taiwan Co., Ltd. 2nd Floor, Chung-Ling Bldg., No. 363, Sec. 2, Fu-Hsing S. Road, Taipei 2-733-2383Shihlin Electric & Engineering Corp. No. 75, Sec. 6, Chung Shan N. Rd., Taipei 2-834-2662China Ryoden Co., Ltd. Chung-Ling Bldg., No. 363, Sec. 2, Fu-Hsing S. Road, Taipei 2-733-3424

Singapore Mitsubishi Electric Singapore Pte. Ltd. 152 Beach Road #11-06/08, Gateway East, Singapore 189721 295-5055Mitsubishi Electric Sales Singapore Pte. Ltd. 307 Alexandra Road #05-01/02, Mitsubishi Electric Building, Singapore 159943 473-2308Mitsubishi Electronics Manufacturing Singapore Pte. Ltd. 3000, Marsiling Road, Singapore 739108 269-9711Mitsubishi Electric Asia Coordination Center 307 Alexandra Road #02-02, Mitsubishi Electric Building, Singapore 159943 479-9100

Malaysia Mitsubishi Electric (Malaysia) Sdn. Bhd. Plo 32, Kawasan Perindustrian Senai, 81400 Senai, Johor 7-5996060Antah MELCO Sales & Services Sdn. Bhd. 3 Jalan 13/1, 46860 Petaling Jaya, Selangor, P.O. Box 1036 3-756-8322Ryoden (Malaysia) Sdn. Bhd. 2nd Fl., Wisma Yan, Nos. 17 & 19, Jalan Selangor, 46050 Petaling Jaya 3-755-3277

Thailand Kang Yong W atana Co., Ltd. 15th Floor, Vanit Bldg., 1126/1, New Petchburi Road, Phayathai, Bangkok 10400 2-255-8550Kang Yong Electric Co., Ltd. 67 Moo 11, Bangna-Trad Highway, Km. 20 Bang Plee, Samutprakarn 10540 2-312-8151MELCO Manufacturing (Thailand) Co., Ltd. 86 Moo 4, Km. 23 Bangna-Trad, Bangplee, Semudparkarn 10540 2-312-8350~3Mitsubishi Elevator Asia Co., Ltd. Bangpakong Industrial Estate, 700/86~92, Moo 6 Tambon Don Hua Roh, 38-213-170

Muang District Chonburi 20000Mitsubishi Electric Asia Coordination Center 17th Floor, Bangna Tower, 2/3 Moo 14, Bangna-Trad Highway 6.5 Km, 2-312-0155~7(Thailand) Bangkawe, Bang Plee, Samutprakarn 10540

Philippines International Elevator & Equipment, Inc. Km. 23 West Service Road, South Superhighway, Cupang, Muntinlupa, 2-842-3161~5Metro Manila

Australia Mitsubishi Electric Australia Pty. Ltd. 348 Victoria Road, Postal Bag No. 2, Rydalmere, N.S.W. 2116 2-684-7200

New Zealand MELCO Sales (N.Z.) Ltd. 1 Parliament St., Lower Hutt, P.O. Box 30-772 Wellington 4-569-7350

Representatives

China Mitsubishi Electric Corp. Beijing Office SCITE Tower, Rm. 1609, Jianguo Menwai, Dajie 22, Beijing 1-512-3222Mitsubishi Electric Corp. Shanghai Office Room No. 1506-8, Shanghai Union Building 100, Yanan-East Street, Shanghai 21-320-2010

Korea Mitsubishi Electric Corp. Seoul Office Daehan Kyoyuk Insurance Bldg., Room No. 1204 #1, Chongno 1-ka, 2-732-1531~2Chongno-ku, Seoul

Viet Nam Mitsubishi Electric Corp. Ho Chi Minh City Office 8 B2, Han Nam Officetel 65, Nguyen Du St., 1st District, Ho Chi Minh City 8-243-984

MITSUBISHI ELECTRIC OVERSEAS NETWORK (Abridged)

MITSUBISHI ELECTRIC CORPORATIONHEAD OFFICE: MITSUBISHI DENKI BLDG., MARUNOUCHI, TOKYO 100-8310, FAX 03-3218-3455

Documents

VOL. 76/SEP. 1996 - Mitsubishi Electric