STANAG391 Tutorial v1.0

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Flying High with STANAG3910 A STANAG3910 Tutorial July 10, 1999v1.01 GmbH Page 2 GmbH Document History Version Cover Date Created by Description 1.00 July 10, 1999 Douglas Ullah and Creation of Document Hansjoerg Frey 1.01 Jult 10, 1999 Reformated AIM WorldwideAIM GmbHSasbacher Str. 279111 Freiburg, Germany+49-761-45 22 [e-mail] Sales OfficeTerofalstrasse 23 a80689 Muenchen+49-89-70 92 92 [e-mail] AIM-USA69 Ginger Woods RoadPO Box 338Valley, NE 68064www.aim-online.com [e-mail] UKLincoln Rd, Cressex Business ParkBucks HP12 3RB, England+44-1494-44 68 [e-mail]3910 Overview Page 3 GmbH Notice The information that is provided in this document is believed to be accurate. No responsibility 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 Page 4 GmbH Flying High with STANAG3910 Overview and History As the EF2000 Typhoon enters the production stage of its development, STANAG3910, EFAbus will get its first chance to prove itself by ...

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• Publié par: Zuwyor
• Nombre de lectures: 57
• Langue: English

Extrait

Flying High with   STANAG3910   A STANAG3910 Tutorial  

July 10, 1999 v1.01

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  Document History    Version Cover Date Created by Description 1.00 July 10, 1999 Douglas Ullah and Creation of Document Hansjoerg Frey 1.01 Jult 10, 1999 Reformated  

www .aim-online.com  

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AIM Worldwide AIM GmbH Sasbacher Str. 2 79111 Freiburg, German [phone] sales @ aim-online.com Munich Sales Office Terofalstrasse 23 a 80689 Muenchen [phone] [e-mail]   AIM-US 69 Ginger Woods Road PO Box 338 Valley, NE 68064 866-AIM-1553 866-AIM-A429 salesusa @ aim-online.com AIM U Lincoln Rd, Cressex Business Par Bucks HP12 3RB, England [phone] salesuk @ aim-online.com

STANAG3910 Overview  Page 3  

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                                                                    Notice   The information that is provided in this document is believed to be accurate. No responsibility 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 will get its first chance to prove itself by meeting the mission critical avionics requirements for this highly sophisticated fighter aircraft.   Since it was established at the early stages of the programme that the data transfer capacity of the MIL-STD-1553B bus was not going to fulfil the requirements, STANAG3910 was selected by the Eurofighter (UK, Germany, Italy & Spain) consortium in 1989 to meet the demanding Avionics Systems needs of such an aircraft.   Very simply STANAG3910, EFAbus is based on using the existing MIL-STD-1553B, 1Mbit/sec dual redundant Low Speed (LS) bus augmented by a High Speed, (HS) Fibre Optics (Reflexive Star Topology) 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 for Data Transfers under the control of these Action Words.   The bus architecture comprises a Bus Controller (BC) with up to 31 Remote Terminals (RTs). Each device can have a LS/HS connection as shown in Figure 1. Bus Concept Bus Remote Remote Bus Controller Terminal Terminal Monitor               LS-BIU   HS-BIU LS-BIU   HS-BIU LS-BIU   LS-BIU   HS-BIU

Dual Redundant LS-Bus (Electrical)

         F/O F/O Reflexive Reflexive Star Coupler Star Coupler Dual Redundant HS-Bus (Optical)

  In the case of the EF2000 implementation, RT Sub-address 26 (decimal) on the LS bus is reserved as the HS Sub-address. All HS transfers are initiated via the LS bus with Command and Status words for the HS bus being transferred as LS datawords. The transfer types are as defined in the MIL-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 bus approach 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. In 1988, this first draft was submitted to the AVS WP in Brussels. Following this in 1989, a project specific variant known as EFAbus was issued. This is the version used today (with some updates) for the EF2000 aircraft project.   STANAG3910 Overview  Page 5  

   GmbH It should be appreciated that this standard was adopted due to the lack of a truly available off the shelf High Speed Data Bus for Avionics applications. This, in conjunction with the reasons listed below, 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 Electro Magnetic Interference (EMI) and reduce the susceptibility to lightning, radiation and Nuclear Electro Magnetic Pulses (NEMP). The STANAG3910 standard defines the physical layer of the HS bus for both Electrical and Fibre Optical implementations. The fibre optic topologies can be implemented in several ways:   • Transmisive Star • Reflexive Star (used for EF2000, Typhoon) • Linear Bus   Figure 2  shows s a Transmissive Star Coupled bus. The advantages to this topology is that you have 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 (four fibres per dual redundant Terminal).

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 TX     Terminal  #1  RX  

 TX   Terminal  #2  RX               TX   Terminal  #n  RX

           Transmissive Star Coupler         

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             GmbH Figure 3 shows a Reflexive Star Coupled bus topology. The advantages of such a topology include a 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 is required in each Terminal.   TX      Terminal  #1  RX    Splitter      TX   Terminal  #2  RX    Splitter  

   TX   Terminal  #n  RX    Splitter  

    Figure 4 shows a Linear Tee Coupled Bus. The advantages of such a topology are that expansion is 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.      

Coupler

Coupler

Coupler

Coupler

 TX   Terminal  #1  RX   

 TX   Terminal  #2  RX         TX   Terminal  #n  RX

Coupler

Coupler

  Reflective Star Coupler

   GmbH The Reflexive Star Optical implementation selected for the EF2000 uses the following parameters:   • Wavelength 770850 nm • Transmitter Output -0.5 +/- 3.5dbm (peak) • Receiver Sensitivy - 37 dbm (peak) • Bit Error Rate < 10 10   • Fibre 200/280 µ m, step index, numerical aperture 0.24   Transfer Protocol   Specifically the LS bus handles the transfer protocol. Once the LS Bus Controller further has initiated an HS LS BC messages can be initiated. STANAG3910 defines several HS transfer types, which are shown in the figures below:   LS Bus Command HS Action Status Next Word Word * * Word # #   Transfer S  T I   HS Message Frame   H Bus

* * : MIL-STD-1553B Response Time ( 4 ... 12 µs )  # # : MIL-STD-1553B Intermessage Gap ( > 4 µs )  T I  : HS Transmitter Initialise Time (24 ... 32 µs )     Figure 5  HS BC and RT to BC Transfer      

      LS Bus Command HS Action Next Word Word # #   Transfer   HS Bus  T I   HS Message Frame

Figure 6  HS BC Broadcast Transfer

  ## : MIL-STD-1553B Intermessage Gap ( > 4 µs )  T I  : HS Transmitter Initialise Time ( 24 ... 32 µs )                           Page 8  

 

           GmbH LS Bus Command HS Action Status Command HS Action Status Next Word Word (RX) * * Word #   #   Word Word (TX) * * Word      #   #   Transfer

R I /R IOUT  

T I  HS Message   Frame

HS Bus       * * : MIL-STD-1553B Response Time ( 4 ... 12 µs )  ## : MIL-STD-1553B Intermessage Gap ( > 4 µs )  T I  : HS Transmitter Initialise Time (24 ... 32 µs )   Figure 7  HS RT to RT             LS Bus  Command HS Action Command HS Action Status Next Word Word (RX)   #   #   Word Word (TX) * * Word      #   #   Transfer

HS Bus

T I  HS Message Frame   R I /R IOUT  

  Figure 8  HS RT Broadcast     HS Mode Code transfers use the BC to RT or BC Broadcast transfer of one action word and optionally one data word. At this point in time the standard does not define HS Mode Codes with an additional data word. The Mode Codes currently defined are as follows:   Hex Value HS Mode Code   03 Initiate HS Self Test 04 HS Transmitter Shutdown 05 Override HS Transmitter Shutdown 08 Reset HS Terminal 09 HS Receiver Initialise OA HS Transmitter Initialise   To perform an HS Status check a RT to BC transfer has to be issued via the LS bus. The Word Count maybe variable but no transactions take place on the HS bus. The HS Status Word is in the first 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.  

STANAG3910 Overview  Page 9  

   GmbH Figure 9 shows the HS Status Check sequence sent on the LS bus.       Command Status HS Status Last HS HS BIT Data Data       Word Word Word Action Word Word Word 1   Word 1   * *     Both the LS and HS buses have strict Protocol timing requirements defined. In the case of the LS bus this is the same as STANA3838 (equivalent to MIL-STD-1553B). For the HS bus the following protocol timing requirements are defined:   Transmitter Initialise Time 2432 µ s Receiver Initialise Time 24 µ s max. Receiver Initialise Timeout 185 +/- 15 µ s Data Streaming Timeout 4.15 ms +/- 20% Inter Transmission Gap 2 µ s   HS Action Word   The HS Action Word is a data word sent by the BC to HS Sub-Address of one or all Terminals on the LS bus. It controls any HS data transfer and contains any HS Mode Code specification as required by the BC. The HS action word is always a One Word Message on the LS bus generated by the BC. The HS Action words for Data Transfers and Mode Codes are shown in Figures 10 & 11.            MSB                       LSB     15 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 A  1: use HS Bus B   • HS T/R: HS Transfer Direction 0: Receive  1: Transmit   • HS Message Identify: 7 Bit HS 'Subaddress'   • HS Block Count: Number 32 Word blocks contained in HS Message Frame      MSB                LSB     15 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 A  1: 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 Page 10  

 

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  HS Status Word   The HS Status Word definition is shown in Figure 12 below.     MSB                      LSB     15 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 Error •  Bit 13 : HS Receiver Active  Bit 12 : HS Receiver not ready ( optional)  Bits 9...11: reserved (set to 0)   • HS TX Status Bit 3 : HS Transmitter active  Bit 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 Bus Standard. The HS frame length is a minimum of 624 bits up to a maximum of 65,648 bits depending on 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 1s (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 to identify the start of HS frame.   Bit 0 Bit 1 Bit 2 Bit 3

   

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