MIL-STD-1553 is a military standard that defines the physical and logical layers, and a command/response time division multiplexing of a communication bus used in military and aerospace avionic platforms for more than 40 years.
A MIL-STD-1553 multiplex data bus system consists of a Bus Controller (BC) controlling multiple Remote Terminals (RT) all connected together by a data bus providing a single data path between the Bus Controller and all the associated Remote Terminals.
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.
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:
- Direct Coupling – Short Stub where the node must be less than 30cm from the bus
- 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.
Today, MIL-STD 1553 is primarily used in systems integration of flight controls, missile system testing, and air traffic control testing. It’s also used as on-board aircraft system monitoring, satellite test systems, shipborne and aircraft simulators.
While 1553 may be a slower technology to what is currently available on the market, 1553 continues to be the communication method of choice for DoD because of its high reliability in critical situations.
Want to learn more? Tonex offers Offensive MIL-1553 Exploitation Training, a 2-day training program address MIL-1553 security issues.
Offensive MIL-1553 Exploitation Training is a unique training course which offers pen testers the ability to assess and exploit the security of MIL-1553 enabled systems. The training covers different varieties of MIL-STD-1553 systems, devices, assessing their attack surfaces, analyzing cybersecurity test and evaluation, risk assessment with RMF and analyzing exploits for them. This class is based on theatrical systems.
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