User guide

Communication Capabiliites
94
890 USE 108 00 August 2001
Modbus Plus Address Routing Schemes
Address
Schemes
Between Modbus
and Modbus Plus
Modbus devices use addresses of one byte in the range 1 ... 255. Modbus Plus
devices are addressed in the range 1 ... 64, with five consecutive routing bytes
contained in each message. When a Modbus message is received at the Modbus
port on the A984-145, E984-245/255/265/275/285 Controllers, the single-byte
address contained in the message is converted into a five-byte routing path for
Modbus Plus. The five bytes of routing are imbedded in a Modbus Plus message
frame as it is sent from the originating node.