rtd cpuModules CMA24BT, User Manual

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42 CMA24BT cpuModule BDM-610000087 Rev A
Dual Serial Port Modes
The serial port connectors can be configured as dual serial ports in the BIOS. This enhancement in dual
RS-232 comes at the cost of losing the DSR and DTR signals, which are only available in single RS-232
mode.
The mapping between the connectors and COM port numbers is shown in Table 16. The supported
combinations of serial port modes are listed in Table 17, which also includes a reference to the
corresponding connector pinout.
Table 16 Dual Serial Port Connections
Connector COM A COM B
CN7 COM 1 COM 3
CN8 COM 2 COM 4
Table 17 Dual Serial Port Modes
COM A COM B Pinout
Reference
Echo Mode
RS-232 RS-232 Table 18 —
RS-422 RS-422 Table 19 —
RS-485 RS-485 Table 20 echo canceled
RS-485 RS-485 Table 19 with echo 1
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 18 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 CTS1 COM A - Clear To Send 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 RTS1 COM A - Request To Send out 4