The bus coupler is connected between MIL-STD-1553B bus and bus devices (controllers, monitors and terminals). The purpose of the bus coupler is to reduce reflections, protect the bus and maintain impedance of the bus by employing a transformer and a pair of fault-isolation resistors. The transformer with a turns ratio of 1.41:1 maintains the 78ohm impedance of the bus while the resistors protect the bus from the potential shorts from devices on the stub.

 

The MIL-STD-1553B standard recommends that coupling devices connected directly to the bus without bus couplers should be avoided because of the potential hazards of direct connections and very limited stub lengths (less than 0.3m). Terminators or self-terminating couplers must be used at both ends of the bus.

 

Greenwood bus couplers are available in 1 to 8 stub boxed style and 1 to 4 stub in-line models. The boxed couplers employ encapsulated transformers for maximum performance and reliability, the transformers and resistors meet MIL-SPEC requirements. Furthermore, after boxed couplers are assembled, a potting compound with low out-gassing characteristics permanently secures all components in place.

 

All Greenwood couplers have been tested by Test Systems Inc, in accordance with SAE AS4117 to confirm meeting the MIL-STD-1553B specifications. Greenwood 's market focus for these databus components is test rig and vehicle applications. Most Greenwood boxed coupler types are available from stock, otherwise lead times average three weeks.

 

Special versions are available, e.g. dual terminated. Greenwood can also supply flight rated boxed and in-line bus couplers manufactured by Sanmina-SCI.