Length of read in in python-gpib

[Madhusudan Singh]

Further, if I use 131072 (2^17) as the length, I get an error :

Traceback (most recent call last):
  File "takedata.py", line 74, in ?
    x=sr.querytrca(srs,1,0,4000,131072)
  File "/home/labmonkey/code/oledpmt/sr830.py", line 62, in querytrca
    trca=sr.read(n)
  File "/usr/lib/python2.3/site-packages/Gpib.py", line 22, in read
    self.res = gpib.read(self.id,len)
gpib.error: Read Error: ibrd() failed

Following this, an attempt to run the script again chokes at the first
(harmless - just setting some instrument parameter - ibwrt() fails) gpib
command and then locks the bus, freezing the whole system unless I reboot
the system. This has happened twice.

I am using the Agilent82357a USB to GPIB convertor. Have used it for
numerous purposes with the same setup, but the library seems to be choking
on this new application. The instrument I am trying to use is an SR830
lockin amplifier.