Emerson ControlWave Instruction Manual page 43

RS-232 Cable
Guidelines
Revised Aug-2015
ControlWave I/O Expansion Rack Instruction Manual
Pin
8
9
Use the "null modem" cable for full-duplex (PPP protocol)
communications when connecting a ControlWave to a PC. (See top part
of Figure 2-21.)
Figure 2-21. Full-duplex and Half-duplex Cable
Use the half-duplex cable (shown in the bottom part of Figure 2-21)
when connecting the ControlWave to another ControlWave series unit
(again, with the exception of the CW_10/30/35 units).
Observe the following guidelines when constructing RS-232
communication cables:
Ensure that DCD is high to transmit

Set CTS to high to transmit.

If the port is set for full-duplex operation, RTS is always ON.

Ensure that DTR is always high when port is active

When port is set for half-duplex operation, CTS must go low after

RTS goes low.
Installation
RS-232
Signal RS-232 Description
CTS Clear to Send Input
RI Ring Indicator
2-31