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
I am getting some very peculiar behavior with the serial interface on
my GPS rcvr (Z3816A).
I have tried several computers and several different GPS utilities
(GPS-DOS2, Sat Stat, GpsCon, etc.).
To date, the only thing that works is Sat Stat on a windows 2000 computer.
I am using a Null modem
