Mil-Std-1553B Interface & Test-Setup Design
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012Mil-Std-1553B Interface & Test-Setup DesignMr. Sameer Vaghela*, Prof. Y. B. Shukla#* E.C. Department, SardarVallbhbhai Institute of Technology, VasadGujarat Technology University, Gujarat, India.# E.C. Department, SardarVallbhbhai Institute of Technology, VasadGujarat Technology University, Gujarat, India.AbstractB) ApplicationIIJJEERRTTMIL-STD-1553 is a military standard that specifies therequirements for a digital command/response time divisionmultiplex data bus for integration of aircraft/spacecraftsubsystems. Simply stated, digital command / response timedivision multiplexing is the transmission of informationbetween subsystems over a pair of wires with differentsubsystems transmitting at different points in time in responseto commands. The 1553 Standard contains several sectionsand describes the method of communication, the data busrequirements and the electrical interface requirements forsubsystems connected to the data bus. This paper contains theinterfacing of different hardware element within a singledigital mil-std-1553B bus & explains how to testify & validateterminal elements with the help of Tester/Simulator.A tri-service version, MIL-STD-1553A was released in 1975,modified to MIL-STD-1553B in 1978 and utilized in the AirForce F-16 and the United States (US) Army AH-64A ApacheAttack Helicopter. Notice 2, released in 1986 and supersededNotice 1 released in 1980. Notices 3 and 4 did not alter thecontents of the standard, but only provided a title change.MIL-STD-1553B has become the internationally acceptednetworking standard for integrating military platforms.Keywords: Mil-std-1553 Bus, Remote Terminal, Testing,CouplingThe 1553 data bus is the most commonly used military databus today. It is used in systems where data integrity andsystem reliability are critical.It is heavily used inaircraftavionics and stores and in ships, submarines andground vehicles such as tanks. The data busis also beingused in space in numerous satellites and the SpaceStation and in somecommercial applications such asreactors, subway cars and oil drilling.[8]I. IntroductionC) Why 1553?MIL-STD-1553B is the military specification defining aDigital Time DivisionCommand/Response Multiplexed DataBus. The 1553 databus is a dual-redundant, bidirectional,Manchester II encoded databus with a high bit error reliability.All bus communications are controlled and initiated by a mainbus controller. Remote terminal devices attached to the busrespond to controller commands MIL-STD-1553B definesspecifications for terminal device operation and coupling,word structure and format, messaging protocol and electricalcharacteristics. A) HistoryMIL-STD-1553B was developed from the growingcomplexity of integrated avionics systems and thesubsequentincrease in the number of discrete interconnectsbetween terminal devices. The first draft of a standard in 1968by the Aerospace Branch of the Society of AutomotiveEngineers (SAE) laid the foundation for the US Air Force’sadoption of MIL-STD-1553 in 1973.www.ijert.orgLinear LAN Network Architecturemakes it ideallysuited for connecting distributed devices, reduce cablingrequirement, reduce overall weight, reduce conservingspace, provides system design & maintenance/flexibilityallowing ease of add & removal of node.Capacity of Redundancy by providing fault tolerance.Support for Dumb & Smart Nodes by providinginterfaces to sensors/actuators.It provides High Level of Electrical Confidence asnodes can be easily/safely isolated from network,reducing potential for damage to equipments.Generated real-time Determinism, this is the mostcompelling reason for which designer choose this as itscommand/response protocol which guarantees real-timedeterminism.1
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012Figure 1: Typical Block DiagramII. Hardware Components [1]Table 1: Bus CharacteristicsMIL-STD-1553B defines three types of terminal devices thatare allowed on the bus: The Transmission Media. Remote terminals. Bus controllers. Bus monitors.There is now no maximum length for the main data bus.Following transmission line design practices and carefulplacement of the stubs can yield working systems with themain bus length of several hundred meters.It is highlyrecommended that the bus be modeled and tested to insure itsoperation and performance characteristics.IIJJEERRTTi) 1553 CablingThe MIL-STD-1553B definition of a data bus is “atwistedshielded pair transmission line made up of amain bus and anumber of attached stubs”.Shielding limits signal interferencefrom outsidesources and the twisted pair maintainsmessageintegrity through noise canceling.Figure 2: Terminal DevicesA) Transmission MediaThe transmission media, or data bus, is defined as a twistedshielded pairtransmission line consisting of the main bus and anumber of stubs. Thereis one stub for each terminal connectedto the bus. The main data bus isterminated at each end with aresistance equal to the cable's characteristicimpedance (plus orminus two percent). This termination makes the databusbehave electrically like an infinite transmission line.Stubs, which are added to the main bus to connect theterminals, provide“local” loads and produce impedancemismatch where added. Thismismatch, if not properlycontrolled, produces electrical reflections anddegrades theperformance of the main bus. Therefore, the characteristicsofboth the main bus and the stubs are specified within thestandard. Table summarizes the transmission mediacharacteristics.MIL-STD-1553B specifies that all devices in thesystem willbe connected to a redundant pair ofbuses, providing analternate data path in the eventof damage or failure of theprimary bus path. Busmessages only travel on one of the busesat a time,determined by the bus controller.Properly terminating the main data bus on each end makes thebus appear like an infinite line.Stub loading effects can beminimized on the bus by properly designed coupling.ii) 1553 CouplingCoupling connects a terminal device to the main data bus viainterconnecting buses calledstubs. Connecting terminals createa load on the main bus, creating impedance mismatchesandresultant signal reflections that can distort and degrade signalquality on the bus. Systemerror rate performance and goodsignal to noise ratio require a balance between stubimpedancebeing low enough to provide adequate terminal signal levelsbut high enough toreduce signal distortion from reflections.The main bus is terminated at each end of the cable with thecharacteristic impedance to minimize reflections caused bytransmission line mismatch. With no stubs attached, the mainbus looks like an infinite length transmission line with nodisturbing reflections. When the stubs are added to connectterminals the bus is loaded locally and a mismatch occurs,which can result in reflections. The degree of mismatch andwww.ijert.org2
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012resulting signal distortion is a function of the absoluteimpedance Z presented by the stub and terminal impedance.To minimize signal distortionit is desirable to maintain ahigh stub reflectedimpedance into to the main bus. At thesame time the impedance needs to be low so that adequatesignal power will be delivered to the receiver.A trade-off and compromise between these conflictingrequirements is necessary to achieve the specified signal tonoise ratio and system error rate performance. In addition tothis trade-offs, careful consideration must be made in thedetermination of the type of connector used to connect theterminal to the bus.MIL-STD-1553B allows two methods of coupling terminaldevices to the main bus:a. Direct couplingb. Transformer coupling.B) Remote TerminalRemote terminals are defined within the standard as “Allterminals notoperating as the bus controller or as a busmonitor”.Therefore if it is not acontroller, monitor, or themain bus or stub, it must be a remote terminal.The remoteterminal comprises the electronics necessary to transferdatabetween the data bus and the subsystem. So what is asubsystem? For1553 applications, the subsystem is the senderor user of the data beingtransferred.In the earlier days of 1553, remote terminals were used mainlyto convertanalog and discrete data to and from a data formatcompatible with thedata bus. The subsystems were still thesensor that provided the data andcomputer, which used thedata. As more and more digital avionics becameavailable, thetrend has been to embed the remote terminal into thesensorand computer.IIJJEERRTTA remote terminal typically consists of a transceiver, anencoder/decoder,a protocol controller, a buffer or memory,and a subsystem interface. In amodern black box containing acomputer or processor, the subsystem interface may consist ofthe buffers and logic necessary to interface to thecomputer'saddress, data, and control buses. For dual redundantsystems,the most prevalent in today's applications, twotransceivers and two encoders/decoders would be required.Theremote terminal consists of all the electronics necessary totransfer data between the data bus and the user or originator ofthe data being transferred.Figure 3: Coupling MethodsDirect& Transformer CouplingDirect coupling connections are wired directly to the buscabling. The isolationresistors and transformer are internal tothe terminal device, not requiringadditional couplinghardware. Direct coupling connections can only be usedwithstub lengths of less than 1 foot.Isolation resistors providesome protection for the main bus in the event of a stuborterminal short, but MIL-STD-1553B cautions the use of directcoupling becausea terminal short could disable the entire bus.Direct stubs can also causesignificant impedance mismatcheson the bus.Transformer coupling utilizes a second isolation transformer,located external tothe terminal device, in its own housing withthe isolation resistors. Transformercoupling extends the stublength to 20 feet and provides electrical isolation,betterimpedance matching and higher noise rejectioncharacteristics than directcoupling. The electrical isolationprevents a terminal fault or stub impedancemismatch fromaffecting bus performance.Figure 4: Remote Terminal ArchitectureBut a remote terminal must be more than just a data formatter.It must be capable of receiving and decoding commands fromthe bus controller and responding accordingly. It must also becapable of buffering a message worth of data, detectingtransmission errors and performing validation tests upon thedata, and reporting the status of the message transfer. Notice 2to the standard also requires that a remote terminal be capableof performing a few of the bus management commands(referred to as mode commands). For dual redundantapplications, it must be capable of listening to, and decoding,commands on both buses at the same time.www.ijert.org3
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012A remote terminal must follow the protocol defined by thestandard. It can only respond to commands received from thebus controller (i.e., it speaks only when spoken to). When itreceives a valid command, it must respond within a verysmall, closely defined amount of time. If a message doesn’tmeet the validity requirements defined, then the remoteterminal must invalidate the message and discard the data (notallow it to be used by the subsystem). In addition to reportingstatus to the bus controller, most remote terminals today arecapable of providing some level of status information to thesubsystem.i)Functional Elements3) Protocol Sequencer & Subsystem InterfaceThe encoder/decoder is transparent to data word type andcontents. Therefore, it passes the words with the errorindications to the message processor for further analysis. Themessage processor continues the analysis by performingcommand word decoding, address validation, data flowdirection (transmission or reception), data reception, messagelength validation, and data storage when receiving data anddata transmission for transmitting data. A major task of theprotocol sequencer is the subsystem interface control. Thesubsystem interface complexity may vary from a singleparallel or serial handshake for communication to a DMA orshared RAM interface to buffer RAM and/or mail memory.C) Bus ControllerThe bus controller is responsible for directing the flow of dataon the databus. While several terminals may be capable ofperforming as the buscontroller, only one bus controller maybe active at a time. The buscontroller is the only one allowedto issue commands onto the data bus.The commands may befor the transfer of data or the control and managementof thebus (referred to as mode commands).IIJJEERRTTA MIL-STD-1553 terminal may be specificallydesigned as astandalone remote terminal, embedded remote terminal, buscontroller or bus monitor. Flexible terminal designs oftenperform both buscontroller and remote terminal functions.This is achievable because of their intelligence (processingpower) and a common front end design compatible with bothremote terminal and bus controller functions. This section willdescribe the functional elements of a generalized terminaldesign.[6]data words. Bit patterns other than the sync pattern arechecked to verify proper Manchester encoding. The number ofbits per word and parity are verified to complete the bit andword analysis.Typically, the bus controller is a function that is containedwithin someother computer, such as a mission computer, adisplay processor, or a firecontrol computer. The complexityof the electronics associated with thebus controller is afunction of the subsystem interface (the interface tothecomputer), the amount of error management and processingto beperformed, and the architecture of the bus controller.[4]Figure 5: Remote Terminal Functional ElementsThe four major functional elements are: The analog receiver/transmitter The digital encoder/decoder The subsystem interface.D) Bus Monitor1) Analog Transmitter/ReceiverThe analog transmitter/receiver functional element is primarilythe analog front end required to interface the terminal's digitallogic with the data bus. This section includes the couplingtransformer and fault isolation resistors required for a directcoupled connection to the data bus. The 1553 receiverprovides low level noise rejection and a digital outputcompatible with the digital logic that follows in the decoder.2) Encoder/DecoderThe encoder/decoder is used to analyze the data bits andwords required for data transfer on the receiver side of theterminal. The squared up signal from the receiver is input tothe decoder, which senses bit timing to decode the syncpattern, data bits, and parity to identify command/status orA bus monitor is a terminal that listens (monitors) to theexchange ofinformation on the data bus. The standard strictlydefines how busmonitors may be used, stating that theinformation obtained by a busmonitor be used “for off-lineapplications (e.g., flight test recording,maintenance recordingor mission analysis) or to provide the back-up buscontrollersufficient information to take over as the bus controller.”Amonitor may collect all the data from the bus or may collectselected data.The reason for restricting its use is that while amonitor may collect data, itdeviates from the commandresponse protocol of the standard, in that amonitor is a passivedevice that doesn’t transmit a status word andtherefore cannotreport on the status of the information transferred.Busmonitors fall into two categories: A recorder for testing. A terminal functioning as a back-up bus controller.www.ijert.org4
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012III) Testing [1]MIL-STD-1553B terminal testing has been conducted bydesigners and the US Air Force SEAFAC Laboratories atWright Patterson AFB. In the past, the proof that a terminal'sdesign was acceptable, required it to pass the SEAFACValidation Tests. Several years ago, the governmentrecognized that a single laboratory could not test everyone'sdesigns. With the increasing numbers and suppliers of 1553embedded terminals and the extensive number of chip setsbeing developed, something had to be done to distribute thetesting load while maintaining the highly successful designverification effort.Figure 6: Production test plan board & softwarei) Purposeii) Levels of Testing(4) Systems Integration Testing.The purpose of systems level testing is to insure that allelements of the bus network *play" together. This level oftesting is usually centered around the operation of the buscontroller's software and its ability to manage the data flow onthe bus. This level of testing is generally performed in aSystems Integration Laboratory.(5) Field/Operational Testing.Regardless of the amount of integration testing performed, thefinal design verification is the actual field/operational testingof the system. Often this is the first time the actual subsystems(as opposed to simulated systems) are interfaced to the busnetwork. For military applications this level of testing isusually referred to as Development Test/Operational Test(DT/OT). This level of testing is systems oriented andencompasses a total examination of all systems functions fromthe man/machine interface to the accuracy to the systemsperformance.IIJJEERRTTThe purpose of any form of testing is to determine the qualityor functional capability of an item. In the testing of 1553devices, the purpose of the test procedure is to verify that thedesign does meet the 1553 specifications and that the optionsimplemented have been done so correctly. In the early days of1553 implementation, there were few, if any, standardcomponents (e.g. transceivers, encoders/decoders, protocolsequencers, etc.) available for the designers to use. Therefore,designers were developing their own based upon theirinterpretation of the standard.The levels of testing can be identified as follows:developmental, design verification, production, systemsintegration, and field/operational testing. These levels may beapplied to the remote terminal, bus controller, monitor, oractual bus system (cable, couplers, stubs, etc.).These levels are discussed as follows:(1) Developmental Testing.Developmental testing begins with the breadboard of thedesign. It is used to determine the circuits operation and toeliminate any design flaws. This level of testing also includesthe testing of the circuits operating margins and tolerancelimits usually over the required operational requirements (e.g.,temperature range, etc.).(2) Design Verification.For design verification, usually a preproduction unit issubjected to a series of tests designed to verify that the unitsatisfies the requirements of the 1553 standard and the optionsspecified in the system specification. This level is generallythe most extensive phase of testing.iii) Test RequirementsTest requirements for terminals can be divided into two maintopics: electrical interface tests (including noise tests), andprotocol tests. The electrical interface tests apply to allterminal types (remote terminals, bus controllers, andmonitors), whereas the protocol tests are a function of the typeof terminal being tested. All tests should be applied to each ofthe buses when the terminal contains redundant buses. Someof the tests are used to "characterize" the terminal rather thatto verify compliance to the standard and the results should beincluded in the Interface Control Document. Each of the testsis summarized as follows:1) Electrical Interface Tests(3) Production Testing.Production testing is generally referred to as "end item" or"acceptance" testing, but can also be applied to in progress orsubassembly items. It is assumed that the design has beenpreviously verified and that this level of testing is performedto verify that all of the circuitry is functioning properlyincluding mode code operation, error message validation, andany other special sequences that can normally be performed.The specifications called out in the standard define therequirements at the connector pins of the terminal. Thesepoints are defined by point A in figures 9 and 10 of MIL-STD1553B. It is important to note that all of the specifiedrequirements are for the terminal itself and are not to bemeasured with the terminal connected to a system where theywould be dependent on other system elements. The electricalwww.ijert.org5
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012interface tests can be subdivided into four parts: input, output,isolation, and noise tests.characterized. This includes the measurement of the statusword response time.The input tests include:a) Input Polarityb) Input Impedancec) Input Signal Amplituded) Zero Crossing Distortione) Rise/Fall Timesf) Common Mode Rejectiong) Input Bit Rate StabilityThe terminal should also be tested for its ability to respond tosuperseding commands. The message validation of theterminal needs to be examined by injecting messages withvarious error conditions.The validation criterion which needs to be tested includes:a) Sync Errorsb) Encoding Errorsc) Bit Count Errors (word length)d) Parity Errorse) Word Count Errors (message length)f) Gaps (discontinuous data)The output tests include:a) Output Polarityb) Output Amplitudec) Zero Crossing Stabilityd) Rise/Fall Timese) Distortion, Overshoot and Ringingf) Output Symmetry/Tailoffg) Output Noiseh) Power on/off Noisei) Output Bit Rate Stabilityb) Bus Controller Protocol Tests.2) Protocol TestsIIJJEERRTTSince terminals functioning as monitors need not be designedwith a transmitter, the output tests do not always apply. Theisolation tests are used to verify the input and output isolationbetween buses in a redundant bus design. The requirement isgiven as the ratio in dB between the voltage on the active busand the voltage on the inactive bus.Testing of the bus controller function requires priorknowledge of the bus controller’s software. The first step is toverify that the bus controller is capable of issuing the desiredcommand list and data. This is often difficult to do, especiallyin systems where events occurring on the bus or data wordpatterns cause the insertion of various aperiodic messages intothe command list. Also an important part of this test is tomonitor that the controller never issues invalid commands(1553) OR commands prohibited by the systems specification(i.e., dynamic bus control mode codes). The bus controllermust also be tested to insure that it transmits on only one busat a time.The protocol tests are performed as a function of the terminaltype. Bus controllers which are also capable of performing asa remote terminal (e.g. while acting as the backup buscontroller) need to be tested for both functions. The protocoltests for the remote terminal and bus controller aresummarized as follows:a) Remote Terminal Protocol Tests.The first step in testing the remote terminal is to verify that theterminal responds properly to all the legal (valid) informationtransfer formats including BC-RT, RT-BC, RT-RT, modecommands with and without data words (receive andtransmit). These formats should be tested with all subaddressand word counts implemented in the terminal. Allimplemented mode code operations also need to be tested. Ifthe terminal is designed to recognize illegal commends, thenall of these commands, and their specified response, need tobe tested. The unique terminal address of the terminal needs tobe checked by sequencing the address through allcombinations while issuing commands to all the otheraddresses.If possible, the proper processing of the normal valid terminalresponses must be tested. The bus controller must also betested for its processing of abnormal or invalid responses.These may include: no response; improper status bits; worderrors (sync, encoding, parity, etc.); discontinuous data words;and word count errors. The bus controllers timingcharacteristics also needs to be verified. This includes theminimum intermessage gap and the minimum no responsetime out. As can be seen, knowledge of the software operationis required in order to perform most of the bus controllerprotocol tests.IV) FUTURE WORKFrom this paper we conclude that communication between anysubsystems present in satellite or spacecraft is possible morereliably with the help of mil-std-1553 bus. Now onwards thereal interfacing and programming are to be done on the basisof special RT (Hybrid, STIC, and ACE). It also comes fromdifferent vendors in different modules as ACTEL provides itsIP core instead of its interfacing card as RT, and you caneasily interface through core as compare to card. We can alsocheck its terminal by tester/simulator, and correct it if anyerror persists.In addition, if the broadcast option has been implemented, allof these tests need to be repeated for the broadcast address.The terminals timing characteristics need to be verified andwww.ijert.org6
International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 1 Issue 10, December- 2012V) REFERENCE1) DDC MIL-STD-1553 DESIGNER’S GUIDE105 Wilbur PlaceBohemia, New York 11716-2482SIXTH EDITION2) MILSTD1553.com - Complete Online Reference for MILSTD-15533) An Interpretation of MIL-STD-1553B, Doc 1553Interpretation.fm, ver 2.0, 27 Aug 2004, 10:27, SBSTechnologies4) MIL-STD-1553 Tutorial v1.3 December 2002,AIM GmbHSasbacher Str. 279111 Freiburg, Germany5) http://www.ddc-web.com6)MIL-STD-1553 Tutorial (1600100-0028), CondorEngineering, Inc.Santa Barbara, CA 931018) http://www.mil-std-1553.org/IIJJEERRTT7) Mil-Std-1553 Aircraft Internal Time Division Command /Response Multiplex Data Bus OverviewbyLeroy Earhart,MSEE President, TEST SYSTEMS, Inc.Phoenix, Arizona602-861-1010www.ijert.org7
adoption of MIL-STD-1553 in 1973. A tri-service version, MIL-STD-1553A was released in 1975, modified to MIL-STD-1553B in 1978 and utilized in the Air Force F-16 and the United States (US) Army AH-64A Apache Attack Helicopter. Notice 2, released in 1986 and superseded Not
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Electromagnetic Interference: MIL- STD-461F Ballistic Shock: MIL-STD-810G Life Fire: MIL- STD-810G Explosive Environment: MIL -STD 810G Altitude to 60,000ft: MIL -STD 29595 Explosive Decompression: MIL- STD-810G Salt fog: MIL -STD 810G Sand and Dust requirements: MIL-STD-810G Extreme operating . environments . Commercial NATO
MIL-C-16173 MIL-L-19140 STANDARDS MILITARY MIL-STD-22 MIL-STD-248 MIL-STD-271 MIL-STD-278 MIL-STD-”731 MIL-STD-792 MIL-STD-1684 - Paper, Kraft, Treated (Fire Resistant).-Corrosion Preventive Compound, Solvent Cutback, Cold-Application. - Lumber and Plywood, F’ire-retardentTreated.
3.4 ARINC 429 88 3.4.1 ARINC 429 Overview 88 3.4.2 ARINC 429 Architecture Realisation 90 3.5 MIL-STD-1553B 91 3.5.1 MIL-STD-1553B Overview 91 3.5.2 MIL-STD-1553B Word Formats 92 3.5.3 Bus Controller to Remote Terminal (BC-RT) Protocol 94 3.5.4 Remote Terminal to Bus Controller (RT-BC) Protocol 94 3.5.5 Remote Terminal to Remote Terminal (RT-RT .
vocabulary materials such as graded readers, which go up through approximately the 4,000-word-family level, to more challenging texts such as newspapers, classic novels, and academic texts, at the .
