Hardware reference guide

CPU Modules
160
35013379 11/2011
Modbus Port Modem Support
Modbus Port 1 has full modem interfacing ability. Modbus Port 2 RTS/CTS
connections function properly for normal non-modem communications but do not
support modems.
Modbus Ports Pinout Connections
The following figure shows the Modbus port pinout connections for 9-pin and 25-pin
connections.
Modbus Ports Pinout Connections for Portable Computers
The following figure shows the Modbus port pinout connections for 9-pin portable
computers.
The following is the abbreviation key for the above figures.
TX: Transmitted Data DTR: Data Terminal Ready
RX: Received Data CTS: Clear to Send
RTS: Request to Send NC: No Connection
DSR: Data Set Ready CD: Carrier Detect