[time-nuts] HP5335A GPIB questions.

Orin Eman orin.eman at gmail.com
Sun Mar 22 01:35:43 EDT 2015

The 5335A is fussy.  FWIW I used the following init string:


Important: I then wait for 125 ms; that being the total time for IN,FN1,WA1
to execute per the 5335A manual.  Only then, do I try to read data from the
instrument.  Pay careful attention to the times that commands take and
don't try to access the 5335A before that time... expect it to sulk

After reading the first result, then I loop reading results.  I have an
additional delay of 100ms before reading each result.  The comment in my
code is: "5335A seems to sulk if we read too soon".

I was using a real Prologix Ethernet GPIB adapter when I wrote this code.

The delays are extremely important.  The 5335A can and will hang if you
don't wait long enough.  In keeping with that, *do not* set your adapter to
do an automatic read after sending data over the GPIB.

Another thing to note is that the 5335A likes some kind of termination on
its commands.  I used <CR> using the ++eos=1 command to the Prologix.  The
unescaped '\n' in my init string ends the string to be sent over GPIB and
'\r' is appended by the Prologix adapter.  There is no need to send EOI
after a command and the 5335A does not send EOI after the last character it
sends.    You have to read up to '\n' instead.

You also want to make sure you don't timeout any read from the adapter
before the gate time that is set on the 5335A.  I used a 3s timeout with a
gate of about 2s.

I think that covers the gotchas that I know of!


On Sat, Mar 21, 2015 at 7:24 PM, Luke Mester <lmester60 at gmail.com> wrote:

> I recently bought a HP5335A counter and have some questions about operating
> the instrument with GPIB.
>  I expect that a lot of time nuts are using this instrument and may be able
> to help. Please excuse me if this is a stupid question. This is my first
> GPIB instrument.
> After each GPIB command that I send I've found that I then need to send an
> RE (reset) command. If I Don't send RE the instrument takes no readings and
> has a blank display. For example I send FN9 to select period and  get no
> readings until RE is sent. Is this normal?
> I'm currently talking to it with a USB to GPIB adapter and a terminal
> program.
> Since I had no idea if the GPIB interface was functional I didn't want to
> buy an expensive GPIB adapter. I build the cheapest GPIB adapter that I
> could find on the internet. It's possible that this is causing problems.
> It emulates a Prologix adapter. Here is a link if you're interested.
> HTTP://http://www.dalton.ax/gpib/
> I've found that this adapter does not properly report the serial control
> line status. Because of this, Timelab won't detect the GPIB adapter.
> You can get Timelab to work if you choose the "Acquire from counter in talk
> only mode" option.
> --
> Luke Mester
> http://mesterhome.com/
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