MILSTD1553

MIL-STD-1553, formally known as "Aircraft Internal Time Division Command/Response Multiplex Data Bus," is a standardized military data bus used for interconnecting electronic subsystems in military aircraft and spacecraft. Developed by the United States Department of Defense, it was first released in 1973. The standard defines the electrical characteristics, signal levels, timing, and protocols for a serial communication bus.

The MIL-STD-1553 bus operates as a master-slave system, with a single bus controller managing all communications. Remote terminals are the devices connected to the bus, such as weapons systems, navigation equipment, and flight controls. The bus controller initiates all data transfers, either by requesting data from a remote terminal or by sending data to one. This deterministic nature ensures predictable message timing, crucial for real-time control systems.

The bus uses a redundant configuration, typically with two independent buses, to provide fault tolerance. If one bus fails, the system can switch to the other. Data is transmitted in words, which can be command words, status words, or data words. These words are transmitted serially in Manchester II biphase code. The standard specifies a data rate of one megabit per second. MIL-STD-1553 is widely adopted in military aviation and has seen use in various international platforms as well. Its reliability and established nature have made it a persistent standard despite the advent of newer communication technologies.