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vrf SPOLLs and ComputerBoards

Question asked by VRFuser on Jun 1, 2000

This is one for anyone who is a ComputerBoards user.  I
have developed a vee prog that controls an HP8753C network
analyzer - essentially a looping routine that performs a
sweep, and returns the trace data.  This prog was developed
on a PC running Win95 using an HP HPIB card (the PCI one I
think).  The final intention was to allow this prog to be
run from either the desktop machine with the HPIB card or a
laptop with a ComputerBoards PCMCIA card.

Okay, in order to provide the necessary flexibility I used
a control pin on the 1st direct IO object to the 8753 to
set the address (i.e. either 7XX or 14XX).

The sweep time is long - between 1-2 seconds, so I used the
status bytes to tell me when the sweep has finished.  I
haven't figured out a neat way of floating the SRQ (no
control input to allow address to be changed), so I used a
SPOLL to check for the status byte.  This I do in a Direct
IO object with the WAIT transaction (set to SPOLL rather
than time in secs).

Everything works fine using the HPIB card.  Things are not
so good with the ComputerBoards card (a PCM-GPIB). 
Essentially after 500 odd successful sweeps + transfers
(point at which it fails is random, non-repeatable) I get a
time out on the read back i.e. I ask for the trace data
back and expect to read 801 points.  The readback IO object
times out as I guess it cannot get the data.

I was running with ComputerBoards ver 3.3 driver (never had
any problems before) and thought that maybe their latest
driver would help ver 3.51.  Tried 3.51 and the prog wont
work at all.

It is a nightmare.  Anyone any suggestions?


Andy Street
Tel: +44-1-865-273178

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