GE Industrial Solutions GE ZENITH SERIES MDU - Manual (Page 38)

Branch Circuit Monitoring System (BCMS)
GE Z ENITH C ONTROLS
MDU Owner’s Manual
601 S HILOH R OAD January 2013
Plano, TX 75074 Page 38
1. ModBus Data Interface
The normal data protocol is ModBus RTU and uses a 4-wire plus shield, multi-point
EIA/TIA-422-B (RS-422) interface. The default communications parameters for the
interface are 9600 baud, 8 bit, even parity, and 1 stop bit. Parity can be changed.
Optionally, the BCMS data interface can be strapped for 2 wire plus shield RS-485, and
2 wire plus ground RS-232. Note that RS-232 is only possible if there is only one BCMS
(there is no multi-point or daisy chain) and the distance to the computer is less than 20
ft. The communications parameters remain the same. Address 1 is the default base
address. It is changed from the service port.