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~!