[Premium-Rx] WJ 8712A Serial Cable Question

[Gary Geissinger]

Spencer,
 
I have a WJ-8712; I suspect that the WJ-8712A pinout is the same.
 
The WJ-8712 kinda looks like a standard RS-232 device; however, it's not "exactly" the same.
 
The RS-232 data connections in the WJ-8712 A2J3 25 pin connector are:
 
Pin 2: TX data out of the '8712
Pin 3: RX data into the '8712
Pin 7: Signal ground
 
On a standard PC the RS-232 connections in the 25 pin connector are:
 
Pin 2: TX data out of the PC
Pin 3: RX data into the PC
Pin 7: Signal ground
 
The handshake jumpers that short pin 4 to pin 5 and the others that short pins 6,8.and 20 together are given as not installed at the factory.
 
The differences surround the "optional" RS-422 / RS-485 signals that can also be placed in the same connector:
 
Pin 10: 422RXA
Pin 11: 422RXB
Pin 18: 422/485 TX/RXA
Pin 25: 422/485 TX/RXB
 
While these are not connected in typical PC/AT compatible RS-232 cards with 25 pin connectors, a fully equipped RS-232 interface connects pins 11, 18, and 25 for current loop data.
 
A typical 25 pin null modem cable has the following connections:
 
Pin 1 to Pin 1
Pin 2 to Pin 3
Pin 3 to Pin 2
Pins 4,5 to Pin 8
Pin 8 to Pins 4,5
Pin 6 to Pin 20
Pin 20 to Pin 6
Pin 7 to Pin 7
 
>From this is appears that a null-modem cable would do the trick.  
 
I don't know about the '8712A', but in the 8712 you have to set A2S1 switch 4 to the off (up) position to enable the RS-232 interface and disable the CSMA interface.
 
Good Luck,
 
Gary WA0SPM

________________________________

From: premium-rx-bounces at ml.skirrow.org on behalf of spencer bahner
Sent: Wed 1/24/2007 7:43 PM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] WJ 8712A Serial Cable Question



Prem-Rxers-

Can anyone advise if the serial cable for use with the 8712A receiver is a
standard serial cable? Is it a straight-through serial cable or a
null-modem?

Thanks!

Spencer Bahner N7UMO
Seattle



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