Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 Installation Instructions, PRIOR to Firmware rev. 3.0 - Manual (Page 41)

Publication 1404-IN007D-EN-P - October 2004
Powermonitor 3000 41
Optional RS-232 Communications
Powermonitor 3000 units with a catalog number ending in -232 are
equipped with an RS-232 serial communications port in addition to
the native RS-485 port. The RS-232 communications standard supports
point-to-point communications among two stations or nodes. The
RS-232 port supports Allen-Bradley DF1 half-duplex slave and Modbus
RTU slave communications at data rates of 1200 to 19.2k baud. You
must select either optional RS-232 communications or native RS-485
communications. The two ports do not operate at the same time.
The optional RS-232 communications port is a DCE (data
communications equipment) type device. It requires a straight-through
RS-232 cable to connect with personal computers, programmable
controller serial ports, and other DTE (data terminal equipment)
devices. It requires a crossover cable for connection to a modem or
other DCE devices. No terminating resistor is required.
The maximum cable length is 15.24 meters (50.0 feet). Refer to the
following wiring diagrams for cable pinout information for
constructing your own cable using DB-9 and/or DB-25 connectors.