What 1553 is: a single conductor
MIL-STD-1553 is the US Department of Defense standard for the serial data bus of mission systems: a command/response protocol where nothing travels unless the bus controller asked for it.
Determinism is the essence: the bus controller (BC) schedules every transfer, the remote terminals (RT) — up to 31 — answer only when polled, and the bus monitor (BM) watches for recording and diagnosis. The medium is a shielded twisted pair with transformer coupling, in dual redundancy: if bus A degrades, traffic moves to bus B. Manchester II coding carries 1 Mbit/s with 20-bit words and messages up to 32 data words.
Published in the 1970s and consolidated in the 1553B revision of 1978 — adopted by NATO as STANAG 3838 — it remains the mission bus of aircraft, helicopters, vehicles and ships: slow on paper, irreplaceable where certifiable behaviour is required. In the catalog, interfaces arrive on OpenVPX, PMC/XMC and VME, often alongside ARINC 429 on the same unit.
The standard in brief
- Body: US DoD · NATO STANAG 3838
- Revision: 1553B (1978)
- Speed: 1 Mbit/s, Manchester II
- Medium: shielded pair, transformer coupled
- Redundancy: dual bus (A/B)
- Nodes: 1 BC · up to 31 RTs · BM
- Word: 20 bits · messages up to 32 words
The roles on the bus, item by item
Three roles, one protocol: who commands, who answers, who listens.
BC — Bus Controller
The only one initiating transfers: it polls terminals according to the mission schedule and manages failover to the spare bus. The system's determinism is its job.
RT — Remote Terminal · max 31
The equipment's interface: it answers BC commands by transmitting or receiving up to 32 data words per message, with the status word confirming the outcome.
BM — Bus Monitor
It listens without transmitting: mission recording, testing and diagnosis. In the catalog interfaces the three roles coexist on the same board, selectable in software.
The 1553 interface, integrated and tested
1553 channels on the platform you need — VPX, VME, mezzanines — with selectable BC, RT and BM: our engineering team starts from your specification and delivers the system tested.
