[time-nuts] Z3816A RS-232 interface

Gregory Beat w9gb at icloud.com
Fri May 11 13:12:58 EDT 2018

Check TWO things.

1.) Has the RS-232 level converter (1488/1489, MAX232, etc.) failed?

2.) What MODE is your Z3816A, SCPI?  The GPSCon software places Z3816A into SCPI.

This is discussed in K8CU’s notes, below:

K8CU Notes - HP Z3816A GPS Frequency Standard Receiver


greg, w9gb


I am getting some very peculiar behavior with the serial interface on
my GPS rcvr (Z3816A).
To date, the only thing that works is Sat Stat on a windows 2000 computer.
I am using a Null modem and set the monitor computer to 9600-8N1.
Other computers and/or utilities seem to give irregular behavior.

I have looked at the signals with a scope and they seem borderline OK.
The signals (Rx and Tx) swing a bit more than +/- 7 V. There is also some
digital noise riding on the lines.
I also notice that the -15 Vdc line on the internal power supply is not
working (it reads about + 1.2 V).
Someone on the web I found a posting claiming that the -15 Vdc line is not
needed for the Z3816A.

Any help would be appreciated.
1. Is 9600-8N1 correct?
2. Could the lack of the -15 Vdc line be the root cause?
3. Has anyone managed to use GpsCon with a Z3816A?
Thanks much for any input!

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