[time-nuts] SatStat and HP 58534A

[Murray Greenman]

Phil,

It is very likely that the program WILL work with the 58534A. However,
there are several steps to take before you can be sure whether it will
or won't.

First, you must ensure that your RS422 to RS232 adaptor is working
correctly. The TX output should sit idle at -9V (or thereabouts), and be
connected to the PC's RX input, which should be close to 0V. Similarly,
the same should apply to the PC TX out and adaptor RX in. This might
sound obvious, but it is fundamental to the operation, and is easy to
check. You may need to use a 'null modem' adaptor to set things right.

Next, you must ensure that you have the correct comms speed and parity.
Again, fundamental, but please check. Run a dumb terminal program on the
PC, one that's easy to use and quick to change the settings on (e.g. Win
3.1 Terminal) - Hyperterminal is too slow and inconvenient. Start with
the settings which are the default for the 58534A, and take careful note
of the parity it expects. All you need to do is press ENTER on the
keyboard. If you get an 'SCPI>' response, well and good. If there's no
response, or it's garbled, change the settings and try again. There's no
point in trying SatStat until you pass this hurdle.

Finally, start SatStat, and use the settings you discovered in the
previous step.

If things prove really difficult, and you can't find the correct rate,
resort to an oscilloscope, and time the bits as the start-up message
comes out. This will also confirm for you which pin is the TXD. All
units should send 'SCPI>' some time soon after power is applied.

It really is simple if you take the steps logically. I've debugged comms
to six different GPSDOs in this manner - HP Z3801A, Symm 58503B, HP
Z3815A, Chongho GPSR-A, Samsung GCRU-D and Trimble NTSG50AA. Not all of
them were on the default settings, but they all responded in SCPI
protocol eventually.

73,
Murray ZL1BPU