AMETEK CW Series Programming Manual - Manual (Page 17)

RS-232 Interface Elgar CW-P Series
4-2 Programming Manual
4.3 RS-232 Connector
The RS-232 connector is a 9-pin male Subminiature-D type; its pinout is presented
below:
Pin Number Function Input/Output
2 RxD, Receive Data Input
3 TxD, Transmit Data Output
4 Connected to Pin-6
—
5 Signal Ground
—
6 Connected to Pin-4
—
7 Connected to Pin-8 —
8 Connected to Pin-7 —
1,9 Not Used —
When connecting the CW-P to a controller, ensure that the RxD line of the CW-P
connects to the TxD line of the controller, and that the TxD line of the CW-P connects
to the RxD line of the controller. This could be accomplished using a null-modem
cable.
There are two versions of the null-modem cable: a 9-pin/9-pin and a 9-pin/25-pin.
The 9-pin/9-pin cable swaps Pin-2 and Pin-3 between the two ends of the cable, so
that the proper RxD and TxD connections are made, while the 9-pin/25-pin cable
connects Pin-2 to Pin-2 and Pin-3 to Pin-3. Also, because the CW-P connector has
Pin-4 connected to Pin-6, and Pin-7 connected to Pin-8, the null-modem cables would
connect the following control lines: DSR to DTR and CTS to RTS.