How to improve performance when writing to or reading from a GPIB instruments?

[keng]

I would like to write to and read from to a GPIB instrument. The instrument is a controller which controls a dynamometer to be used in motor performance testing. I have tried to time the TIME (in ms) taken to write to the instrument using a simple written driver program. To my dismay, the return time taken to write (GPIB WRITE) to the instrument is about 600 to 660 ms. I think it is quite long.

Is it something wrong with the way I write to the instrument(ie. GPIB Write) or is it the instrument is quite old (ie. Magtrol 6200 Controller/Readout)?

I have attached a JPEG just to demonstrate how I did it. I use the sequence JUST to time the TIME taken to write to the instrument but I
don't use it in my real application program. My computer specs are as the following.

Pentium II 350 Mhz.
Windows 98 SE
Labview 6.1 base package
4 MB video RAM
256 MB Memory.
3 connected GPIB devices: (power supply, dynamometer controller and power analyser)

I have also tried adjusting the GPIB Devices properties in Control Panel. I make a tick on the Readdress box and Terminate Read on EOS and change the EOS Byte to 10 but still it does not improve the performance.

I have read about "timing issues" in this discussion forum but I have yet to find the "right" answer to my problem.

Does anyone has a better solutions to this problem?

Thanks,
keng

[mikeporter]

Unfortunately, there isn't a whole lot you can do to speed-up a slow GPIB instrument since each byte in the transfer has to be sent and acknowleged individually. No matter how fast your computer is, the instrument will slow things down to the rate that is can respond to transfers. One thing to look into is check to see if the device itself is programmable. In other words can you give the thing a list of operations to perform and then simple trigger the operation?Mike...

[keng]

Hi Mike,
thanks for replying.
Although the instrument is old, can I calibrate it to get the data faster?

Recently, I have read a number of tips in improving GPIB device performance and one of them is using multithread vis. Does it help?

Thanks,
keng

[Dennis_Knutson]

There's probably nothing you can do to improve the performance of an old instrument. It's really dependent on the gpib chipset they used and the internal firmware. You could check with the manufacturer to see if there's the possibility of a firmware upgrade. The one thing you haven't mentioned is the model number of the gpib board you're using. Some low cost ones (like NI's GPIB-PCII) are very slow.

[keng]

Hi Dennis,

Thanks for your comment. Yes, my system controller is a NI PCI-GPIB (NI-488.2 for windows 98) board. Oh, I didn't know that it is a slow card too (just learning to use NI products recently).

If I can't get to upgrade the gpib instruments firmware, what type of PCI-GPIB card would you suggest?

Thanks,
keng