User`s manual

BDM-610000082 Rev A Chapter 3: Connecting the cpuModule 39

Dual Serial Port Modes

The serial port connectors can be configured as dual serial ports in the BIOS. The mapping between the

connectors and COM port numbers is shown in Table 18. The supported combinations of serial port modes are

listed in Table 19, which also includes a reference to the corresponding connector pinout.

Table 18 Dual Serial Port Connections

Connector COM A COM B

CN7 COM 1 COM 3

CN8 COM 2 COM 4

Table 19 Dual Serial Port Modes

COM A COM B Pinout

Reference

Echo Mode

RS-232 RS-232 Table 20 —

RS-422 RS-422 Table 21 —

RS-485 RS-485 Table 22 echo cancelled

RS-485 RS-485 Table 21 with echo

1. Dual RS-485 mode with echo uses dual RS-422 mode pinout

WARNING The dual serial port mode pinouts of the COM ports are not compatible with previous

generations of RTD cpuModules.

Note The cpuModule has 120 Ohm termination resistors. 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.

When termination is enabled in dual port mode, it is enabled for both ports.

Table 20 COM A (RS-232) and COM B (RS-232)

Pin Signal Function In/Out DB-9

1 DCD1 COM A - Data Carrier Detect in 1

2 DSR1 COM A - Data Set Ready in 6

3 RXD1 COM A - Receive Data in 2

4 TXD2 COM B - Transmit Data out 7

5 TXD1 COM A - Transmit Data out 3

6 RXD2 COM B - Receive Data in 8

7 DTR1 COM A - Data Terminal Ready out 4

8 RI1 COM A - Ring Indicate in 9

9,10 GND Signal Ground — 5