Data acquisition
Dear friends,
I have a trouble with understanding the following. I have a very short
script (shown below) which works fine if I "run" step by step (or line
by line) in Python shell (type the first line/command -> press Enter,
etc.). I can get all numbers (actually, there are no numbers but a
long string, but this is not a problem) I need from a device:
'0.3345098119,0.01069121274,0.02111624694,0.03833379529,0.02462816409,0.0774275008,0.06554297421,0.07366750919,0.08122602002,0.004018369318,0.03508462415,0.04829900696,0.06383554085,
...'
However, when I start very the same list of commands as a script, it
gives me the following, which is certainly wrong:
[0.0, 0.0, 0.0, 0.0, 0.0,...]
Any ideas? Why there is a difference when I run the script or do it
command by command?
===
from visa import *
mw = instrument("GPIB0::20::INSTR", timeout = None)
mw.write("*RST")
mw.write("CALC1:DATA? FDATA")
a=mw.read()
print a
===
(That is really all!)
PS In this case I use Python Enthought for Windows, but I am not an
expert in Windows (I work usually in Linux but now I need to run this
data acquisition under Windows).
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Re: Data acquisition
On Oct 25, 6:29 pm, Nick Dokos wrote: > Shot in the dark: could it be that you have to add delays to give the > instrument time to adjust? When you do it from the python shell, line by > line, there is a long delay between one line and the next. > > Nick Hi, Nick! Thanks! You are right but it was the first thing I thought about. So I have tried to delay using sleep(t) from the time module (I also sent "*OPC?" or "*WAI" commands to a device for synchronization). However, it does not help ... Best, AS -- http://mail.python.org/mailman/listinfo/python-list
Re: Data acquisition
On Oct 25, 6:43 pm, John Gordon wrote: Thanks, John! > Are you running the same python program in both cases? Yes, the same. > Are you in the same directory in both cases? > Does PYTHONPATH and/or sys.path have the same value in both cases? It looks that yes but how can it matter? All I need it is to import the visa module and it works well. > Show us an exact transscript of both executions. There is nothing but "numbers". Or do you mean something else? I do not receive any errors, only different results ... Best, AS -- http://mail.python.org/mailman/listinfo/python-list
Re: Data acquisition
On Oct 25, 6:15 pm, Jean-Michel Pichavant
wrote:
> spintronic wrote:
> > Dear friends,
>
> > I have a trouble with understanding the following. I have a very short
> > script (shown below) which works fine if I "run" step by step (or line
> > by line) in Python shell (type the first line/command -> press Enter,
> > etc.). I can get all numbers (actually, there are no numbers but a
> > long string, but this is not a problem) I need from a device:
>
> > '0.3345098119,0.01069121274,0.02111624694,0.03833379529,0.02462816409,0.0774275008,0.06554297421,0.07366750919,0.08122602002,0.004018369318,0.03508462415,0.04829900696,0.06383554085,
> > ...'
>
> > However, when I start very the same list of commands as a script, it
> > gives me the following, which is certainly wrong:
>
> > [0.0, 0.0, 0.0, 0.0, 0.0,...]
>
> > Any ideas? Why there is a difference when I run the script or do it
> > command by command?
>
> > ===
> > from visa import *
>
> > mw = instrument("GPIB0::20::INSTR", timeout = None)
>
> > mw.write("*RST")
> > mw.write("CALC1:DATA? FDATA")
>
> > a=mw.read()
>
> > print a
> > ===
> > (That is really all!)
>
> > PS In this case I use Python Enthought for Windows, but I am not an
> > expert in Windows (I work usually in Linux but now I need to run this
> > data acquisition under Windows).
>
> Just in case you have a local installation of visa and it silently fails
> on some import,
>
> try to add at the begining of your script:
> import sys
> sys.path.append('')
>
> When using the python shell cmd line, '' is added to sys.path by the
> shell, that is one difference that can make relative imports fail in
> your script.
>
> If it's still not working, well, it means the problem is somewhere else.
>
> JM
Hi!
Thanks! I have just tried. Unfortunately, it does not work ...
Best,
AS
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Re: Data acquisition
Dear friends! Thank you for the discussion. It was really helpful. As mentioned, it was necessary to have a longer delay. Previously I have used a delay of 5 and 10 s but it was not long enough. Now it is 25 s and everything works fine. Thank you again! Best, AS -- http://mail.python.org/mailman/listinfo/python-list
