rtd cpuModule CMC6686GX, User Manual

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Facing the serial port connector, the pinout is:
9 7 5 3 1
GND Rsvd TXD- RXD- Rsvd
GND Rsvd RXD+ TXD+ Rsvd
10 8 6 4 2
NOTE! when using RS422 or RS485 Mode
When using the serial port in RS422 or RS485 mode, the serial
transmitters are enabled and disabled under software control;
the receivers are always enabled.
The transmitters are enabled by manipulating the Request To
Send (RTS*) signal of the first serial port controller. This sig-
nal is controlled by writing bit 1 of the Modem Control Regis-
ter (MCR) as follows:
• If MCR bit 1 = 1, then RTS* = 0, and serial transmit-
ters are disabled
• If MCR bit 1 = 0, then RTS* = 1, and serial transmit-
ters are enabled
For more information on the serial port registers, including the
MCR, please refer to a standard PC-AT hardware reference for
the 16550-type UART.