Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 Installation Instructions, PRIOR to Firmware rev. 3.0 - Manual (Page 38)

Publication 1404-IN007D-EN-P - October 2004
38 Powermonitor 3000
Communication Wiring Methods for connecting communications wiring vary from option to
option. This section provides guidelines for installing dependable
communications wiring for your Powermonitor 3000 system for each
communications option including the native RS-485 communications
port that is part of every Powermonitor 3000.
Native RS-485 Communications Wiring
Every Powermonitor 3000 Master Module is equipped with a native
RS-485 communications port. The RS-485 communications standard
supports multi-drop communications among as many as 32 stations or
nodes. The RS-485 port supports Allen-Bradley DF1 half-duplex slave
and Modbus RTU slave communications at data rates of 1200 to 19.2k
baud.
RS-485 port is also used for Master Module firmware upgrades in the
field.
The native RS-485 communications wiring should be installed in a
daisy-chain configuration. We recommend the use of Belden 9841
2-conductor shielded cable or equivalent. The maximum cable length
is 1,219 meters (4,000 feet). Use of a star or bridging topology is not
recommended and will result in signal distortion unless impedance is
matched for each spur (star topology) or network (bridge topology).
ATTENTION
The user must supply and install special high level
isolation when the possibility of high ground
potential differences exists. This may occur when
communicating with a unit connected to a power
ground mat. Failure to install such isolation may lead
to personal injury or death, property damage or
economic loss.
IMPORTANT
You will need to configure communications for each
communications option. Refer to the Powermonitor
3000 User Manual, publication 1404-UM001, for
detailed communications configuration instructions.