Re: how to program wait_for_srq with linux-gpib in Python

my Raspberry Pi 3 is set up again.

It turns out i should not have changed it.
Because the behaviour in the Python interpreter ( in interactive mode ) remains the same!

However if i write the code into a file and have that executed as a python script everything is working as it should!!!

I could not find it out with my first trial because i only used it in interactive mode before.

The following code is working as it should :

import sys
sys.path.append('/usr/local/lib64/python2.7/site-packages')
import gpib

board  = 0
device = 7
SRQI   = (1<<12)
TIMO   = (1<<14)

print gpib.version()            # Show package version
t = gpib.dev(board,device)      # Open the PREMA 6048
gpib.clear(t)                   # Start out clean
gpib.write(t,"MRO4R2T7Q1L0")    # MR - measurement;
                                # O4 - Ohm 4-wire
                                # R2 - Range 2 K-Ohm
                                # T7 - 4 sec integration
                                # Q1 - SRQ after every measurement
                                # L0 - short output format
n = 10
i = 0
while i <= n:
    	gpib.wait(board, TIMO | SRQI) # Wait SRQI or TIMeOut
        sta = gpib.ibsta()            # Get status
        if (sta & TIMO) != 0:
                print "Timed out"
        else:
                i = i+1
                print gpib.read(t,41)        # read result from DMM
gpib.close(t)



It will also work with 

gpib.wait(board, 0x1000 )

or

gpib.wait(board, 4096 )

No surprise, because the linux-gpib PDF says the ibwait() function expects an integer.


In the interactive interpreter however none of these function calls will work!

They all produce an Error :

gpib.GpibError: wait() failed: One or more arguments to the function call were invalid.

>>>print (1<<12)
4096
>>>print (0x1000)
4096

looks like the interpreter is handling these expressions correctly.

For me its not a big problem because it does not make much sense anyway to complicated stuff interactive through the Interpreter.

But i would still consider this as a bug.
And for quick playing around with the gpib library it would be nice to have all functions working ( like it does in a script ).

@Vince
Did you test it in the interactive interpreter?
Or in a script?


Regards

Joerg

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