TME-104P-CSR-LX800-R1V5.doc Rev 1.5 22 (44)
3.10 Serial Ports
The serial ports are located on two IDC headers "COM1" and "COM2". Adapter cables with standard
DSUB-9 male connectors are available. The ports either work in RS232 or RS485 mode, selectable in
BIOS. When entering Motherboard Device Configuration Æ Serial and Parallel Device
Configurations, COM Port 1 Mode and COM Port 2 Mode can be selected. Termination resistors
for RS485 Mode can be set with Jumpers on pin headers as described in chapter 4.15.
To enable the transmitters of COM1 and COM2 in RS485 mode set the RTS# signal to ‘1’. Depending
on your operating system driver’s logic, this may mean setting a (non-inverted) RTS bit to ‘0’ in your
application software.
The serial ports are programmable in BIOS setup. When entering Motherboard Device
Configuration Æ Serial and Parallel Device Configurations, configuration of the serial ports is
accessible.
The following settings are possible for COM1 and COM2:
• Disabled
• 3F8 / IRQ4 (base address / interrupt channel)
• 2F8 / IRQ3 (base address / interrupt channel)
• 3E8 / IRQ4 (base address / interrupt channel)
• 2E8 / IRQ3 (base address / interrupt channel)
The modes can be switched between RS232 and RS485.
COM1/2 Connector
Connector type IDC10 pin header 2.54 mm
Pin RS232
RS485 Pin RS232 RS485
1 DCD Not used 2 DSR RXD+
3 RXD RXD- 4 RTS TXD+
5 TXD TXD- 6 CTS Not used
7 DTR Not used 8 Not used Not used
9 GND GND 10 +5 Volts +5 Volts
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