rtd cpuModule CMC6686GX, User Manual

Page: 44 / 118

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RS422 or RS485 Serial Port
You may use Setup to configure the second serial port as RS422 or RS485. In this case, you must
connect
P5
or CN8
CN8
to an RS422 or RS485 compatible device.
When using RS422 or RS485 mode, you can use the port in either half-duplex (two-wire) or full-
duplex (four-wire) configurations. For half-duplex (2-wire) operation, you must connect RXD+ to
TXD+, and connect RXD- to TXD-..
The following table gives the pinout of connector P5CN8 or CN8 when RS422 or RS485 modes are
enabled.
Facing
P5
or CN8’s connector pins, the pinout is:
7 DTR Data Terminal Ready out 20
8 RI Ring Indicate in 22
9,10 GND Signal Ground -- 7
NOTE! A 120 ohm termination resistors is provided on the cpuModule. Termi-
nation is usually necessary on all RS422 receivers and at the ends of the
RS485 bus.
If the termination resistor is required, it can be enabled by closing jump-
er JP2.
Connector P5 or CN8 in RS-422/485 Mode
Pin Signal Function in/out DB9
1 -- Data Carrier
Detect
-- 1
2 -- Data Set Ready -- 6
3 RXD- Receive Data (-) in 2
4 TXD+ Transmit Data (+) out 7
5 TXD- Transmit Data (-) out 3
6 RXD+ Receive Data (+) in 8
7 -- Reseved -- 4
8 -- Reseved -- 9
9,10 gnd Signal ground out 5
9 7 5 3 1
GND Rsvd TXD- RXD- Rsvd
GND Rsvd RXD+ TXD+ Rsvd
10 8 6 4 2
Connector
P5
or CN8
in RS-232 Mode