PowerLogic PM-620 - Appendix H-2-Wire Modbus or Jbus

Bulletin No. 3020IM9503R6/98 Power Meter
December 1998 Appendix H—2-Wire Modbus or Jbus
 1998 Square D All Rights Reserved 103
Baud
Maximum Distances
Rate
1–8 Devices 9–16 Devices
1200 10,000 ft. (3,048 m) 10,000 ft. (3,048 m)
2400 10,000 ft. (3,048 m) 5,000 ft. (1,524 m)
4800 10,000 ft. (3,048 m) 5,000 ft. (1,524 m)
9600 10,000 ft. (3,048 m) 4,000 ft. (1,219 m)
19200 5,080 ft. (1,548 m) 2,500 ft. (762 m)
Table H-1
Maximum Distances of 2-Wire Modbus or Jbus
Comms Link at Different Baud Rates
APPENDIX H—2-WIRE MODBUS OR JBUS
COMMUNICATIONS WIRING
When wiring the communications terminals for 2-wire Modbus or Jbus, be
sure to jumper IN+ to OUT+ and IN– to OUT– (figure H-1).
Figure H-1: 2-wire Modbus or Jbus wiring
Power Meter
RS-485
Terminals
➁
OUT–
➂
OUT+
➃
IN–
➄
IN+
➀
SHLD
The table below shows the maximum distance that a daisychain of power
meters communicating via 2-wire Modbus or Jbus can extend. Baud rate and
the number of devices on the daisychain are considerations in calculating the
maximum distance.