GPIB-USB and GPIB-USB-A

[Peter Reeves-Hall]

Hi all,
Doea anyone have experince of the (NI) *USB* GPIB interfaces with labview.
We have just got a GPIB-USB interface (777631-01) and while were were
waiting for it to be delivered NI launched the GPIB-USB-A (778195-01).

Problems :
1) Our old card was a AT-GPIB/TNT (776943-01) (ISA) and the GPIB-USB is
soooo slow in comparison. (over 5 seconds to get ~2K of data from a modern
Spectrum Analyser which did it in <1 second on the old ISA card.)
2) Connection is unreliable, after ~20 repeat readings my VI's loose comms
with the instruments!

(setup: Win 98 se, Dell Optiplex GX1, 400MHz PII, 128Mb)

Q's:
1) Is this normal?
2) Is the GPIB-USB-A any better?
3) Does anyone have the spec's / transfer speed for the GPIB-USB as the NI
we
b page now points that serial no. to the GPIB-USB-A pdf.... ?

Thanks,

Peter

[Peter Reeves-Hall]

"Peter Reeves-Hall" wrote in message
news:8jsh4a$rqg$1@newstest.cc.ic.ac.uk...

> Problems :
> 1) Our old card was a AT-GPIB/TNT (776943-01) (ISA) and the GPIB-USB is
> soooo slow in comparison. (over 5 seconds to get ~2K of data from a modern
> Spectrum Analyser which did it in <1 second on the old ISA card.)

> 3) Does anyone have the spec's / transfer speed for the GPIB-USB as the NI
> web page now points that serial no. to the GPIB-USB-A pdf.... ?

Found the speed of the GPIB-USB from NI tech. support UK (very helpful
people - thanks!)
which is ~300Kb/s (compare with ~650 for the USB-A and ~1200 for the ISA)

[Graham]

Hi Peter,

A's
1)I believe there is a problem with the original GPIB-USB device.

I had a similar problem using the GPIB-USB interface with an HP6624A power supply. The power supply was taking over 15 seconds to do 7 voltage settings and 7 current readings. (setup Win98 se, 550Mhz PIII, 256Mb).
Fortunately, on another project, the OS was Win2000. The GPIB-USB device does not work with Win2000 so we changed all our devices for GPIB-USB-A. Our power supply test (7 setups 7 current reads) now executes in under 2 seconds. So...

2) Yes.

3) No. I am not sure you will get these now either.

Hope this helps.

Graham