MIL STD 1553 what is it and where is it used?

MIL STD 1553 is US Military Department of Defence standard that was initially published in 1973.  The Standard defines the communications network used mainly by Military Vehicles.

Firstly, 1553 is a differential serial bus with some similarities to CAN.  Also, it is a dual redundant data bus.  Each node is connected to each of the redundant buses.  Secondly, if one should fail, communications can still continue.

TYPES of Nodes

There are three types of operating nodes for 1553 Bus

  1. Bus Controller
  2. Remote Terminal
  3. Bus Monitor

 

A Bus Controller initiates all messages, traffic and commands the remote terminals to transmit/receive data.

A Remote Terminal interfaces the 1553 Bus and Sub System Bridge to other 1553 Buses.  It responds to the bus controller and each remote terminal has an unique address.  Also, there can be up to 31 Remote Terminals on a 1553 Bus.

The Bus Monitor is almost like a black box of the system.  It listens to messages and records them.

Methods of Connecting Nodes to Bus

The MIL STD 1553 bus has a fixed bit rate of 1MB per second.  Communication is a half-duplex. The physical cabling is a Twinax shielded cable with 78 ohm termination resistors.  There are two methods for connecting a node to the bus

  1. Direct Coupling – Short Stub where the node must be less than 30cm from the bus
  2. Transformer Coupling – Long Stub where the node must be less than 6m from the bus. This is the preferred method has it offers an improved signal integrity and tolerance.

 

1553 Message Types

The Bus Controller has 5 Types of Messages.  These are

  1. Receive Data
  2. Transmit Data
  3. Broadcast Data
  4. Mode Code
  5. Remote Terminal to Remote Terminal Transfer

 

Each method costs of 16-Bit Words or more, command status or data with a 3 microsecond pulse pause.

Where is MIL STD 1553 is used?

Systems integration of flight controls, missile system testing, and air traffic control testing.  As well as on-board aircraft system monitoring, satellite test systems, shipborne and aircraft simulators.

However, whilst 1553 may be a slower technology to what is currently available on the market.  1553 continues to be the communication method of choice for the Defence Forces because of its high reliability in critical situations.

Alta Data are specialists in MIL-STD-1553 Multi channel interface cards for most computer backplanes and real time Ethernet Converters.  With powerful software that quickly and reliably integrates a network to your application.

For more information on MIL STD 1553 Avionics Bus Analysers, contact us.

 

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