[time-nuts] Lucent KS-24361 RS-422 interface pinout

Graham planophore at aei.ca
Mon Dec 1 20:59:59 EST 2014

I got my pair of REF-0 and REF-1 to lock, REF-1 is now in STBY and the 
REF-0 is on. Thanks to Bob suggesting I wiggle and/or re seat the 
interface cable.

However, I have not been able to "peek" inside using the DIAG port. 
Rather than try the hack suggested by Stu I bought a USB to RS-422 
interface cable, a Startech ICUSB422. It has a DB-9P which plugs 
directly into the DIAG connector BUT on comparing it's pinout to the 
"hack cable" suggested by Stu, it seems that they really don't line up 

This is Stu's suggested "hack cable" from his very informative earlier post

RFTG          PC

DE-9P         DE-9S

7 <---GND---> 5
8 <---------  3 TXD
9  ---------> 2 RXD

The ICUSB422 pinout is as follows (arrows point in direction of data flow)

ICUSB             J8 - Diagnostic
1 TXD- -------->  8 (based on Stu's diagram and description)
2 TXD+ -------->  ??
3 RXD+ <--------  ??
4 RXD- <--------  9 (based on Stu's diagram and description)
5 GND  ---------  7 (based on Stu's diagram and description)
6 NC
7 NC
8 NC
9 NC

But what pins to TXD+ and RXD+ connect to? After much searching and 
looking at a bewildering number of variations of pinouts, I am still 
confused on where these two go. A Wild Ass Guess (WAG) is that 2 TXD+ 
--> 4  and 4 RXD- <-- 5 but I am really uncertain and that is just based 
on one of the pinouts I found in my searchs.

I thought I would be lucky and would just be able to plug and play with 
the ICUSB422 directly to the J8 Diagnostic port but it isn't so; I will 
need to make up an additional adapter to get the right pins going to the 
right pins.

I am hoping someone on the list knows for certain. Failing that I will 
have to poke at it with a scope or DVM tomorrow and to see if I can make 
sense of it.

cheers, Graham ve3gtc

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