Hello everyone,

I would like to control a Keithley source meter with PyVISA in the lab. The operating system is Scientific Linux 5.5, and the Python version is 2.4. I first installed NI-VISA's Linux package (http://joule.ni.com/nidu/cds/view/p/id/2040/lang/en) which was compatible with Scientific Linux 5, and then ctypes from http://python.net/crew/theller/ctypes/ and linux-gpib from http://linux-gpib.sourceforge.net/. After everything was done successfully I fired up an interactive Python session, and typed

import visa

No errors. And then I typed

keithley = visa.instrument("GPIB::25")

but got errors: 

Traceback (most recent call last):

  File "<stdin>", line 1, in ?

  File "/usr/lib/python2.4/site-packages/pyvisa/visa.py", line 287, in instrument

    interface_type, _ = \

  File "/usr/lib/python2.4/site-packages/pyvisa/vpp43.py", line 777, in parse_resource

    byref(interface_board_number))

  File "/usr/lib/python2.4/site-packages/pyvisa/vpp43.py", line 398, in check_status

    raise visa_exceptions.VisaIOError, status

pyvisa.visa_exceptions.VisaIOError: VI_ERROR_LIBRARY_NFOUND: A code library required by VISA could not be located or loaded.

Could anyone please help? Thanks very much~!