STANAG 3910

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Flying High with

STANAG3910A STANAG3910

Tutorial

Nov 2010

v2.01
http://www.aim-online.com/products/hardware/stanag3910-efex/stanag3910-efex.aspxhttp://www.aim-online.com/products/hardware/stanag3910-efex/stanag3910-efex.aspxhttp://www.aim-online.com/products/hardware/stanag3910-efex/stanag3910-efex.aspxhttp://www.aim-online.com/products/hardware/stanag3910-efex/stanag3910-efex.aspx

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STANAG3910 Overview Page 3

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Document History

Version Cover Date Created by Description1.00 July 10, 1999 Douglas Ullah and

Hansjoerg FreyCreation of Document

detamrofeR9991,01tluJ10.1

2.01 Nov 18, 2010 Barbara Waldmann Update addresses

AIM Worldwide

wwwwww..aaiimm--oonnlliinnee..ccoomm

AIM GmbH

Sasbacher Str. 279111 Freiburg, Germany

+49-761-45 22 [email protected]

Munich Sales Office

Terofalstrasse 23 a80689 Muenchen, Germany

+49-89-70 92 92 [email protected]

AIM-USA

Seven Neshaminy Interplex

Suite 211

Trevose, PA 19053

267-982-2600

1-877-5201553

AIM UK

Lincoln Rd, Cressex Business ParkBucks HP12 3RB, England

+44-1494-44 68 [email protected]

[email protected]

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Notice

The information that is provided in this document is believed to be accurate. Noresponsibility is assumed by AIM for its use. No license or rights are granted by implication

in connection therewith. Specifications are subject to change without notice.

Copyright 1999-2002 : AIM

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Flying High with STANAG3910

Overview and History

As the EF2000 Typhoon enters the production stage of its development, STANAG3910, EFAbus willget its first chance to prove itself by meeting the mission critical avionics requirements for this highlysophisticated fighter aircraft.

Since it was established at the early stages of the programme that the data transfer capacity of theMIL-STD-1553B bus was not going to fulfil the requirements, STANAG3910 was selected by theEurofighter (UK, Germany, Italy & Spain) consortium in 1989 to meet the demanding AvionicsSystems needs of such an aircraft.

Very simply STANAG3910, EFAbus is based on using the existing MIL-STD-1553B, 1Mbit/sec dualredundant Low Speed (LS) bus augmented by a High Speed, (HS) Fibre Optics (Reflexive StarTopology) dual redundant bus operating at 20Mbits/sec. The LS bus provides the command and

control of the HS bus by use of Action Words sent over the LS bus. The HS bus is used only forData Transfers under the control of these Action Words.

The bus architecture comprises a Bus Controller (BC) with up to 31 Remote Terminals (RTs). Eachdevice can have a LS/HS connection as shown in Figure 1.

In the case of the EF2000 implementation, RT Sub-address 26 (decimal) on the LS bus is reservedas the HS Sub-address. All HS transfers are initiated via the LS bus with Command and Statuswords for the HS bus being transferred as LS datawords. The transfer types are as defined in theMIL-STD-1553B with no automatic acknowledgement of HS data transfers in the basic protocol.Therefore HS RT status must be polled by the transmitting terminal. It will be seen that this dual busapproach allows the mixed operation of both STANAG3910 and MIL-STD-1553B terminals.

The first draft of this dual speed MIL-STD-1553B based bus was created in Germany during 1987. In1988, this first draft was submitted to the AVS WP in Brussels. Following this in 1989, a projectspecific variant known as EFAbus was issued. This is the version used today (with some updates)for the EF2000 aircraft project.

Bus

Controller

LS-BIU HS-BIU

Remote

Terminal

LS-BIU HS-BIU

Remote

Terminal

LS-BIU

Bus

Monitor

LS-BIU HS-BIU

DualRedundant

LS-Bus(Electrical)

F/OReflexive

Star Coupler

F/OReflexive

Star Coupler

Dual

RedundantHS-Bus(Optical)

Bus Concept

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It should be appreciated that this standard was adopted due to the lack of a truly available off theshelf High Speed Data Bus for Avionics applications. This, in conjunction with the reasons listedbelow, drove the down selection of the STANAG3910, EFAbus for the EF2000, Typhoon aircraft:

Allow evolution from MIL-STD-1553B bus only to Higher Speed Avionics Bus System

Mixing of MIL-STD-1553B/ STANAG3910 Avionics Systems Low Risk approach with first EF2000 Prototypes using MIL-STD-1553B only

Stay with a Deterministic Master/ Slave Protocol

Physical Layer of the HS Bus

The implementation using Fibre Optic technology STANAG3910 HS bus was to eliminate ElectroMagnetic Interference (EMI) and reduce the susceptibility to lightning, radiation and Nuclear ElectroMagnetic Pulses (NEMP). The STANAG3910 standard defines the physical layer of the HS bus forboth Electrical and Fibre Optical implementations. The fibre optic topologies can be implemented inseveral ways:

Transmisive Star Reflexive Star (used for EF2000, Typhoon)

Linear Bus

Figure 2shows s a Transmissive Star Coupled bus. The advantages to this topology is that youhave a favourable Optical Power Budget with a similar Optical Input Signal level for all Terminals.The disadvantages are that expansion is very difficult and two fibre optical cables are required (fourfibres per dual redundant Terminal).

Terminal

#1

TX

RX

Terminal#2

TX

RX

Terminal#n

TX

RX

TransmissiveStar

Coupler

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Figure 3shows a Reflexive Star Coupled bus topology. The advantages of such a topology includea reasonable Power Budget, similar optical input power for all Terminals and a minimal fibre optic-cabling requirement. The disadvantages are that expansion is very difficult and an Optical Splitter isrequired in each Terminal.

Figure 4 shows a Linear Tee Coupled Bus. The advantages of such a topology are that expansionis easy. However the disadvantage is that the receiver input signal level is position dependant which

means receiver must have a wide dynamic range, hence it has a bad Optical Power Budget.

Terminal

#1

TX

RXSplitter

Terminal

#2

TX

RXSplitter

Terminal

#n

TX

RXSplitter

ReflectiveStar

Coupler

Terminal

#1

TX

RX

Terminal

#2

TX

RX

Terminal#n

TX

RX

Coupler

Coupler

Coupler

Coupler

Coupler

Coupler

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The Reflexive Star Optical implementation selected for the EF2000 uses the following parameters:

Wavelength 770850 nm

Transmitter Output -0.5 +/- 3.5dbm (peak)

Receiver Sensitivy - 37 dbm (peak)

Bit Error Rate < 10

10

Fibre 200/280 m, step index, numerical aperture 0.24

Transfer Protocol

Specifically the LS bus handles the transfer protocol. Once the LS Bus Controller further hasinitiated an HS LS BC messages can be initiated. STANAG3910 defines several HS transfer types,which are shown in the figures below:

* * : MIL-STD-1553B Response Time ( 4 ... 12 s )# # : MIL-STD-1553B Intermessage Gap ( > 4 s )TI : HS Transmitter Initialise Time (24 ... 32 s )

Figure 5 HS BC and RT to BC Transfer

## : MIL-STD-1553B Intermessage Gap ( > 4 s )TI : HS Transmitter Initialise Time ( 24 ... 32 s )

Figure 6 HS BC Broadcast Transfer

CommandWord

HS ActionWord

StatusWord

NextTransfer

LS Bus

HS Bus

* * # #

HS Message FrameTI

CommandWord

HS ActionWord

NextTransfer

LS Bus

HS Bus

# #

HS Message FrameTI

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* * : MIL-STD-1553B Response Time ( 4 ... 12 s )## : MIL-STD-1553B Intermessage Gap ( > 4 s )TI : HS Transmitter Initialise Time (24 ... 32 s )

Figure 7 HS RT to RT

Figure 8 HS RT Broadcast

HS Mode Code transfers use the BC to RT or BC Broadcast transfer of one action word andoptionally one data word. At this point in time the standard does not define HS Mode Codes with anadditional data word. The Mode Codes currently defined are as follows:

Hex Value HS Mode Code

03 Initiate HS Self Test04 HS Transmitter Shutdown05 Override HS Transmitter Shutdown08 Reset HS Terminal09 HS Receiver InitialiseOA HS Transmitter Initialise

To perform an HS Status check a RT to BC transfer has to be issued via the LS bus. The WordCount maybe variable but no transactions take place on the HS bus. The HS Status Word is in thefirst data word, HS Action Word in the second word and the HS Built in Test (BIT) in the third word.With regards with BIT word, STANAG3910 EFAbus does not define the usage of these bits.

CommandWord

LS Bus

HS Bus

* * ##

HS Message

Frame

TI

HS ActionWord (RX)

StatusWord

CommandWord

HS ActionWord (TX)

StatusWord

NextTransfer* * ##

RI/RIOUT

CommandWord

LS Bus

HS Bus

##

HS MessageFrame

TI

HS ActionWord (RX)

CommandWord

HS ActionWord (TX)

StatusWord

NextTransfer* * ##

RI/RIOUT

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Figure 9shows the HS Status Check sequence sent on the LS bus.

Both the LS and HS buses have strict Protocol timing requirements defined. In the case of the LSbus this is the same as STANA3838 (equivalent to MIL-STD-1553B). For the HS bus the followingprotocol timing requirements are defined:

Transmitter Initialise Time 2432s

Receiver Initialise Time 24s max.

Receiver Initialise Timeout 185 +/- 15sData Streaming Timeout 4.15 ms +/- 20%

Inter Transmission Gap 2s

HS Action Word

The HS Action Word is a data word sent by the BC to HS Sub-Address of one or all Terminals onthe LS bus. It controls any HS data transfer and contains any HS Mode Code specification asrequired by the BC. The HS action word is always a One Word Message on the LS bus generatedby the BC. The HS Action words for Data Transfers and Mode Codes are shown in Figures 10 &11.

MSB LSB15 14 13 7 6 0

HS A/B HS T/R HS Message Identify HS Block Count

Figure 10

HS A/B: HS Bus Select 0: use HS Bus A1: use HS Bus B

HS T/R: HS Transfer Direction 0: Receive1: Transmit

HS Message Identify: 7 Bit HS 'Subaddress'

HS Block Count: Number 32 Word blocks contained in HS Message Frame

MSB LSB15 14 13 7 6 0

HS A/B HS T/R 0 0 0 0 0 0 0 HS Mode Code

Figure 11

HS A/B: HS Bus Select 0: use HS Bus A1: use HS Bus B

HS T/R: HS Transfer Direction 0: Receive

1: Transmit

HS Mode Code : - 6 HS Mode Codes are defined, for all of them Broadcast is allowed- 9 Mode Codes are reserved- 2 reserved Mode Codes with Data Word

Command

Word

HS Status

Word

HS BIT

Word

Last HS

Action Word

Status

Word* *Data

Word 1

Data

Word 1

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HS Status Word

The HS Status Word definition is shown in Figure 12 below.

MSB LSB15 14 9 8 3 2 0

HS TF HS Receiver Status HS Transmitter Status Reserved

Figure 12

HS TF: HS Terminal Flag ( optional )

HS RX Status Bit 14 : HS Message Frame ErrorBit 13 : HS Receiver ActiveBit 12 : HS Receiver not ready ( optional)Bits 9...11: reserved (set to 0)

HS TX Status Bit 3 : HS Transmitter activeBit 4: HS Transmitter not readies (optional)Bits 5...8: reserved (set to 0)

HS Message Frame

The HS Message Frame contains several elements, which are common with the SAE HS BusStandard. The HS frame length is a minimum of 624 bits up to a maximum of 65,648 bits dependingon the type of HS message transfer, which takes place. It contains a Preamble, Start Delimiter,Headers, Word Count, Information field, Error Detection (CRC) and an End Delimiter.

Figure 13 below shows the make up of the HS Message Frame

Preamble SD FC PA DA WC INFO CRC ED

Figure 13

The following describes the elements, which make up the HS Message Frame

Preamble - This is 40 bits of Manchester Encoded logic 1s (20Mhz square wave signal)and is used for gain control of the receivers, receiver clock recovery and the

decoding of the Start of Frame.

Start Delimiter - This is 8 bits of Manchester Code Violations and contains a unique pattern toidentify the start of HS frame.

Bit 0 Bit 1 Bit 2 Bit 3

ON

OFF

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Headers - Header information is contained within 3 x 16 bits.

The FC/PA comprises a 1 x 16 bit Manchester Encoded Word. The FrameControl (FC) is an 8 bit field set to a pattern of 1100 0000. The PhysicalAddress (PA) is an 8 bit field and specify the RT Address of the transmittingterminal (for BC=31).

The Destination Address (DA) is a 1 x 16-bit word. If the MSB is set to 0Physical Addressing is used. If the MSB is set to 1 Logical Addressing isused. For the EF2000 Logical Addressing is used.

The Word Count Field (WC) is a 1 x 16-bit word and defines the number ofwords contained in the Information Field.

Information Field - The Information Field contains between 32 and 4096 words, each being 16bits. The number of words is always a multiple of 32.

CRC - The HS Message contains a CRC check word, which covers all the wordsbetween the Start and End Delimiter fields. The general Polynomial, which isused for STANG3910, is in accordance with the CRC-CCIT standardPolynomial:

G (x) = x15+x12+x5+1

On the receiving side the CRC generating process is repeated and the received checkword iscompared with the generated checkword. Using this approach the BC or RT has a way to validatethe HS data.

End Delimiter - This is 4 bits of Manchester Code Violations and contains a unique pattern to

identify the end of the HS frame.

Bit 0 Bit 1 Bit 2 Bit 3

ON

OFF

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STANAG3910 Test & Validation

A number of Test and Validation Test Plans documents have been created by the EF2000, AvionicsJoint Team (AJT). These have been created for the suppliers of STANAG3910 Avionics equipmentand components to the EF2000 project to be sure designs and production units conform to the

EFAbus standards. These Test Plans have been created to define, as a minimum, what Protocoland Optical test must be performed before delivering Avionics equipments for use on the EF2000 orthe aircraft rigs prior to flight.

Test Plans include:

EFAbus RT and BC Production Test Plan

EFAbus RT and BC Validation Test Plan

Validation Test is a Super Set of the Production Test Plan

Includes Optical and Protocol Tests

STANAG3838 Test Plans (MIL-HDBK-1553 and SAE AS4113 form part of the EFAbus TestPlans)

Databus Analyser and Modules for STANAG3910 Test & Simulation

As with the MIL-STD-1553B avionics databus, it was recognised by company AIM GmbH thatDatabus Analyser equipments and modules would be a requirement for the development, simulationand production equipments for the EF2000 project. With this in mind, AIM GmbH produced theworlds first commercially available STANAG3910 VMEbus card and Demonstrator System in 1989for potential STANAG3910 Avionics users. Two such systems where supplied to CASA, BritishAerospace for evaluation and test at the conceptual stages of the project.

The Test and Validation requirements of the Protocol and Optical requirements of the STANAG3910standard proved to be a big challenge. AIM GmbH rose to this challenge and created aSTANAG3910 Fibre Optics and Protocol Test System (CTX) which allowed users to testSTANAG3910 equipments against the EFAbus Validation and Production Test plans.

This led to the creation of a Databus Analyser system known commercially as the MBA-90(Modular Bus Analyser). Built using VMEbus cards and controlled via a host PC, the MBA-90STANAG3910 Databus Analyser soon became the Defacto Standard across the entire EF2000project. Today, AIM GmbH enjoy the enviable position as the leading supplier to three of the EF2000Prime Contractors and major Sub-Contractors in the UK, Germany, Italy and Spain for all DatabusAnalysers, VMEbus, VXIbus and PCI based Test & Simulation Modules. This has been no easytask. Much hard work, dedication and private company funding has been put in by the AIM GmbHteam to support STANAG3910 to make

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STANAG 3910