User`s manual

36 CMX34GS cpuModule BDM-610000082 Rev A
Facing the serial port’s connector pins, the pinout is:
RS-422 or RS-485 Serial Port
You may use the BIOS setup utility to configure the serial ports as RS-422 or RS-485. In this case, you must
connect the serial port to an RS-422 or RS-485 compatible device.
When using RS-422 mode, you can use the serial ports in either half-duplex (two-wire) or full-duplex (four-wire)
configurations.
When using full-duplex in RS-422 mode, connect the ports as shown in Table 15.
In RS-485 mode, the connection of the ports is always half-duplex, as the transceivers’ transmitters are
connected to the receivers internally.
9 7531
GND DTR TXD RXD DCD
GND RI CTS RTS DSR
108642
Note The cpuModule has a 120 Ohm termination resistor. Termination is usually necessary on all RS-422
receivers and at the ends of the RS-485 bus. Termination resistors can be enabled in the BIOS setup utility.
Table 15 Full-Duplex Connections
Port 1 Port 2
RXD+ TXD+
TXD+ RXD+
RXD– TXD–
TXD– RXD–