Re: Working with secondary addresses

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> You use a 10s timeout in your python code! Maybe you simple didn't not
> wait long enough. Kidding. :) Better use the provided constants, e.g.
> gpib.T1s

I take your point with that. 10s is an eternity in GPIB transmit terms 
and even 1s should be more than enough.

> But I guess this is a bad end anyway. Since your Perl code is working
> there must be a difference somewhere. Which is very strange, cause these
> are all only wrappers around the C code.

Yes, I think Dave Penler mentioned the same thing. The language is just 
a wrapper around the low level C code, so yes, very strange.

> So probably that is not a problem. Now handle yourself from function to
> function. You have the source code. Instrument it with print statements
> till you see where the difference is. I would do that on the C level.

I added a few more print statements, but its consistently breaking at 
this point:

$ ./test_storage.py
Check for the presence of the device ....
Device present.
Configure FIND ....
Configure INPUT ....
Configure TYPE ....
Configure CLOSE ....
Sleep 1 sec ....
FIND file ....
Traceback (most recent call last):
   File "/home/johnc/Test/linux-gpib/./test_storage.py", line 45, in 
<module>
     gpib.write(cmd_find, fnum)
     ~~~~~~~~~~^^^^^^^^^^^^^^^^
gpib.GpibError: write() failed: You have attempted to write data or 
command bytes, but there are no listeners currently addressed.

which means at this line:

gpib.write(cmd_find, fnum)

which may mean something needs to be changed in here:

cmd_find =  gpib.dev( 0, paddr, 0x7B, gpib.T10s, eot, 0 )

I tried changing the timeout to gpib.T1s or gpib.T30s (not that it 
needed to be any longer) but the exits with the error much too fast for 
the timeout to complete anyway.

Is there any way I can play with manually asserting ATN, sending bytes 
and then de-asserting ATN, then sending some bytes of data, terminating 
with an EOI or reading the returned data? Finally ending with UNT or UNL?



On 31/03/2026 20:13, Christian Grosz wrote:
> John,
>
>> Your example also seems to suggest that 'yes' can be used instead of 1?
> Don't mix up Perl, Python and the /etc/gpib.conf configuration file.
>
> You use a 10s timeout in your python code! Maybe you simple didn't not
> wait long enough. Kidding. :) Better use the provided constants, e.g.
> gpib.T1s
>
> But I guess this is a bad end anyway. Since your Perl code is working
> there must be a difference somewhere. Which is very strange, cause these
> are all only wrappers around the C code.
>
> For python
>
> linux-gpib-4.3.7/linux-gpib-user-4.3.7-orig/language/python/gpibinter.c
> ----
> static PyObject* gpib_dev(PyObject *self, PyObject *args)
> {
> 	int ud = -1;
> 	int board = 0;
> 	int pad = 0;
> 	int sad = NO_SAD;
> 	int tmo = T30s;
> 	int eot = 1;
> 	int eos_mode = 0;
> ...
> ----
>
> there is another set of defaults. For Perl it looks to me like a simple
> wrapper.
>
> So probably that is not a problem. Now handle yourself from function to
> function. You have the source code. Instrument it with print statements
> till you see where the difference is. I would do that on the C level.
>
> Christian
>
>
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