CVR250
SECTION 5
CVR250OPS
20/10/06
www.snellwilcox.com
Version 1 Issue 4
5.4
Connect the RS232/RS422 converter to COM1 or COM2 of the PC and connect this via RS422 cable to the 9
pin ‘D’ on the IQ modular unit. This interface is specifically designed for third party connections into the system.
This allows PC’s or any other serial device access to any of the units within the system. Every active 1RU or
3RU box has one of these ports.
Physical Interface - RS422
Pin 1
GND
TxB
TxA
RxB
RxA
1
6
2
7
3
8
4
9
5
9-way ribbon
1
6
2
7
3
8
4
9
5
N.B.: Connector is
a socket, viewed
from mating face.
Equivalently, this is
a plug, viewed from
the rear, cable face.
For reference, the A signal is at 0 V at line idle, and the B signal at 5V.
Standard Connections
9-way
Connector
FUNCTION
1
Frame Ground
2
Transmit A (Tx-)
3
Receive B (Rx+)
4
Receive Common
5
[No connection]
6
Transmit Common
7
Transmit B (Tx+)
8
Receive A (Rx-)
9
Frame Ground
N.B. The D connector on the Gateway card could
also be configured as RS485. Selection of the
interface format is by a switch on the card.
DOWN i.e. towards the PCB selects RS422
UP
i.e. away from the PCB selects RS485
Switch set to RS485
