ProSoft Technology CompactLogix MVI69E-MBS User Manual page 155

MVI69E-MBS ♦ CompactLogix™ Platform
Modbus Serial Enhanced Communication Module
RS-232: Modem Connection (Hardware Handshaking Required)
This type of connection is required between the module and a modem or other
communication device.
The "Use CTS Line" parameter for the port configuration should be set to 'Y' for most
modem applications.
RS-232: Null Modem Connection (Hardware Handshaking)
This type of connection is used when the device connected to the module requires
hardware handshaking (control and monitoring of modem signal lines).
ProSoft Technology, Inc.
Reference
User Manual
Page 155 of 159