D.-S. Huang, K. Li, and G.W. Irwin (Eds.): ICIC 2006, LNCS 4113, pp. 1133 1138, 2006. Springer-Verlag Berlin Heidelberg 2006

Design and Implementation of a Fast DIO (Digital I/O) and Motion Control System

Gyusang Cho1, Jinkyung Ryeu2,*, and Jongwoon Lee3

1 Dept. of Computer Eng., Dongyang Univ., Youngju, Korea 2 Dept. of IT Electronic Eng., Dongyang Univ., Youngju, Korea

3 Dept. of Railway Control Eng., Dongyang Univ., Youngju, Korea {gyusang, jkryeu, jwlee}@dyu.ac.kr

Abstract. High speed PC-based DIO (Digital I/O) system that consists of a master device and slave I/O devices is developed. The master device, which has PCI interface to a PC, controls all of serial communications, reducing the load on the CPU to a minimum. And the slave I/O devices, which are used as 16 bits input, 16 bits output, and 8bits input-output each, are connected from the master device to one slave, from the slave to the next slave, and to a maximum 64 slaves repeatedly. The master device has 2 rings which can take 64 slaves each. Therefore, total I/O points covered by the master are 2048 points. The slave fea-tures 3 types of input/output function interchangeability by DIP switch settings. Library, application, and device driver software for the DIO system that have a secure and a convenient functionality are developed.

1 Introduction

Many Digital I/Os such as switch input, AC input, relay output and TR output are required in the field of industrial machine, high-accuracy semiconductor instruments, chemical factory and steel factory. PLC (Programmable Logic Controller) [1] is used mostly in these types of I/O processes. In this case, there are some defects such as additional cost fir instruments and the necessities of another OS and of large space for implementing. Moreover, it is difficult to communicate with PC and the length of cable is getting longer. Because of these defects, PC-based I/O cards are used widely. But there also exist some problems such as using limited slots for many I/O cards [2].

Recently, PC-based I/O system using PC as main controller is used widely [3],[4]. Many merits of this method such as real-time controllability, development facility, reliability and scalability make the cost lower. The key criteria of performance in this type of system are wiring between the master device and the slave device, data transfer speed and interfacing PC with the master device.

One-to-one wiring between the master device and the slave device is general, but many I/O cards must be equipped on limited PC slots. In a study using USB for over-coming the defect [5], maximum 64 points can be used by connecting 4 slaves per one USB master port. But the above method has a problem that an additional USB master

* Corresponding author.

1134 G. Cho, J. Ryeu, and J. Lee

device is needed for many points. To overcome this demerit the USB HSIO (High Speed I/O) system which can distribute master and slave by adopting the structure having very high transfer speed and reduced routing was developed[6]. Continued on this research the PCI HSIO system which is more stable and faster than the existing systems and guarantees fixed access time was implemented [7].

In this research, we designed and implemented a DIO (Digital I/O) system which is much better in speed, number of available points and design facility than PCI HSIO [7]. In the body of this paper there are specific methods of design and implementa-tion. The overview of the overall DIO system and the description about the method of hardware implementation for the master and slave devices having simple wiring structure and high operating speed are in Chap 2.

2 Overview of DIO System

2.1 Features of the System

Master device considers I/O of slaves just like accessing memory, so this helps to reduce the burden of CPU and to enhance the communication speed. And it is possi-ble that make the system configuration in a simple form. By using RS-485 commu-nication, it is possible to cut down wiring cost and simplify wiring problem [8].

System is consists of Master and Slave devices as shown in Fig. 1. Master device is installed on PC with PCI interface. The slaves are connected from the master device to one slave, from that slave to next slave, and to other slave, etc. PLX9030 [9] chip is used for PCI communication, and G9001 is used for master device, and G9002 is used for DIO slave devices.

The master device equipped with two G9001 chip can connect maximum 64 slaves each. One is called ring 0 and the other is called ring 1. So the maximum 128 slave can be used. RS-485 communications between the master and slaves have half-duplex way. With 20Mbps communication, the communication time for a slave is about 15.1 micro-seconds and 64 slaves (1024 points of I/O) can be updated within 1 millisecond.

2.2 Wiring and Scalability

The slave device is connected from the master device and another slave device is connected to the slave device, it can be repeated to maximum 64 slave devices in one ring, in case of two rings the master can take 128 slaves. In general, a parallel I/O method has a strong point in a fast response, but the method has a weak point in wring all slave devices to a mater device. A serial I/O method takes advantages in a long distance communication and in total numbers of wire connection, but has disadvantages in the communication speed and load of computation time. Adoption of RS-485 communication method gives a strong point of the serial and the parallel method, and it gives the system an enhancement of communication speed and simplicity in wring.

And, in our system, the way of slave connection is extensible. Several slave types, for example, DIO slave device for I/O device with G9002 chip, motion control slave device for CPU emulation device with G9004 and PCL device with G9003 chip, are operated on a master device. It is possible that, on the one hand, the system communi-cates with DIO devices, on the other hand, communicates with motion control devices.

Design and Implementation of a Fast DIO (Digital I/O) and Motion Control System 1135

Fig. 1. Configuration of DIO system

3 Control of DIO System

3.1 Command and the Memory Map

On the master device the information for controlling the slave devices is document. Having the information about slave makes the master device easier to control slave. Slave device is not holds the information itself but take in charge of only input and output function. The every information on slave is documented on the master device memory. Table 1 show the information which are documented on the master.

Commands to control the master device and the slave device are can be docu-mented on the master device's commands' data in 16 bits of 000-001h. #0100h is for make it have software reset, #1000h is for make it have all system communica-tion, 1100h is for make it have all system communication except the allotted slave., 1200h-123Fh is for make it have assigned device's communication work by bit( 0001 0010 00## ####(#ID assign bit) ), 3000h I/O is for make it have start for communica-tion, 3100h I/O is for make it have end the communication.

3.2 Slave Information

The information which is documented in the master device's memory is recorded after test communication for each slave devices. Upon response to the slaves the informa-tion about the type of device, the connection status and the I/O port are periodically renewed. The type of slave can be in four formats as shown in Table 2. The number of type is decided by the setting value. Each setting is organized to be set by the deep switch. According to this the port which is used in the control is decided and function-ing input or output by the deep switch. When the slaves are connected to the master device the 8 bit information is saved in the memory slot 078h-0B7h as the value cor-responding to the slave setting in Table 2.

Fig. 2 is the actual master device. Fig. 3 is the slave devices that are on operation. LED shows the condition of input and output.

1136 G. Cho, J. Ryeu, and J. Lee

Table 1. Memory map of the master device

Address Write Read 000-001 Command status 002-003 Invalid Interrupt status

078-0B7 Device Info. 8bit for each device. Device #0-#63 Device Info. 8bit for each device. Device #0-#63

0B8-0BF I/O communication error flag 1bit for each device I/O communication error flag 1bit for each device

0C0-0FF Input port change Interrupt settings 4bit for each device Input port change Interrupt settings 4bit for each device

100-1FF I/O port data 8bit for each device I/O port data 8bit for each device

Table 2. Type number settings by DIP switch

Type NO. Setting Port0 Port1 Port2 Port3

type0 00 X X Output

type1 01 Input X X Output

type2 10 X Input Output X

type3 11 Input X X

Fig. 2. PCI master device

Fig. 3. Slave devices for (a) DIO (b) motion control

4 Library Software for DIO System

Library routines for the DIO system are categorized to 4 groups, such as PCI setup and master initialization DIO, slave control, I/O, and ring setting.

PCI setup and master initialization category is consists of five functions. - Initial-izePCI() is used to prepare communication to open device driver DIO.sys, and FinishPCI() closes the communication to the driver. After initialization procedure, StartComm() and StopComm() start and stop I/O communication between the master

Design and Implementation of a Fast DIO (Digital I/O) and Motion Control System 1137

Table 3. Library functions for DIO system

Category Functions PCI settings and

initialization InitializePCI(), FinishPCI(), StartIOComm(), StopIOComm(), Reset()

Slave Control GetDeviceType(),GetAllDeviceType(),GetConnectedDevice(), ClearAllSlave()

Input/Output WriteWord(),WriteByte(),WriteWordBitwise(),WriteByteBitwise(), ReadWord(),ReadByte(),ReadWordBitwise(),ReadByteBitwise()

Ring Control SetRing(), GetRing()

and the slave devices. Reset() is to reset the master device so that all the register of the master can be reset and all slave information can be reset.

Four functions are presented to slave control. GetDeviceType() returns the slave type value when the slave ID is assigned in the argument. GetAllDeviceType() write the type information of all connected slaves(#0-#63) to the slave type information array. GetConncetionDevice() returns the slave number and slave type that are currently con-nected. ClearAllSlave() clears the all slave information in the master devices.

Eight functions that are used to input and output are presented. That functions op-erates in word, byte, and bitwise. WriteWord() and WriteByte() writes in a word and in a byte to a specified slave respectively. WriteWordBitwise() and WriteByteBitwise() writes in a word and a byte to only specified bit to set 0 or 1 respectively. Each Read-Word( ) and ReadByte() returns word and byte data for input. ReadWordBitwise() and ReadByteBitwise() reads the bit data in word and byte from the specified slave.

SetRing() is used to set ring number to 0 or 1, and GetRing() returns a current ring number.

5 Conclusions

In this study, we designed and implemented high speed DIO (Digital I/O) system which has master-slave type structure. Master device is PC-based I/O system with PCI interface. Slave devices can be distributed by using wiring the mater to a slave and a slave to another slave, hence long and complex cabling problem of the existing systems can be solved.

Very fast I/O and simple structure can be accomplished in out system by storing I/O and attribute information of a slave into the master device. As shown in Table 1, our system is superior to the existing methods in communication speed, number of slaves I/O points and applicability of the slave. In our system, the port of a slave can be used for input or output selectively. Therefore the cost of designing and imple-menting is reduced and the users facility is improved.

Software is programmed to operate on Windows XP in this study. We fabricated a device driver with WDM type and programmed a library software having some func-tions such as PCI initialization of DIO system, initialization of the master device, slave control, I/O and ring selection/reset. And also we implemented an application program of dialogue type as an application example.

1138 G. Cho, J. Ryeu, and J. Lee

Under the situation that generalization of PC-based I/O controller and the design of software PLC are going on, high performance with low cost can be accomplished by adopting out system to accurate equipments, control instruments and process control in which digital I/O is required. Moreover, high performance program for controlling I/O which is suited to users circumstances can be implemented by using the functions provided as library forms. Commercialization is anticipated by applying one up tech-nique of our DIO system..

References

1. Kelvin, E. T.: Programmable Logic Controller, IEEE Potential, 3 (1996)14-17 2. Juniper, M.: PC vs. PLC-The Debate Rages On Control Systems -Tonbridge, 13 (6) (1996)

33-34 3. Agostino, C.: Automation of Direct Reduction Plant Using PLC/PC. IFAC Symposium on

Intelligent Components and Instruments for Control Applications, New York (2001) 341-346

4. Hankoo, P.: Application of PC-based Control System to Steel Manufacturing Process, Roll-ing 2001 : 4th Symposium, Japan (2001)

5. Jong W. L.: Distributed Industrial I/O Control System with USB. IEEK Summer Confer-ence Proceeding, Vol. D. (2001) 2362-2364

6. Cho, G. S.: Distributed I/O Control System with USB. 2004 IEEK Summer Conference Proceeding Vol.V. (2004) 1477-1480

7. Cho, G. S.: Development of HSIO (High Speed I/O) System with PCI Interface. 2004 KIEE Summer Conference Proceeding, Vol. D. (2004)2628-2630

8. Motionnet User's Manual, Chapter 1~IV-4, NPM (2004) 9. PCI 9030 Data Book Version 1.4, PLX Technology, New York (2002) 1-198

IntroductionOverview of DIO SystemFeatures of the SystemWiring and Scalability

Control of DIO SystemCommand and the Memory MapSlave Information

Library Software for DIO SystemConclusionsReferences

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