How do I respond to Read requests from multiple GPIB subaddresses?

[Dave_Bell]

I posted a question here yesterday, that was probably unclear. I'd like to refine that a bit:

I am developing an instrument to replace some legacy GPIB equipment. The equipment must respond to data requests on multiple GPIB subaddresses, in non-System Controller mode. There is no a priori way to determine which subaddress the controller might request data from, as it performs many status type checks at various times, and the data my instrument needs to send depends upon which SA was queried.

I have had some Support help that 1) pointed out that the GPIB interface doesn't really support this, but that 2) I may be able to work around the limitation.

So far, I have:

"GPIB Initialization" VI, with
only a Primary address, like "ID0:22".

"Wait" VI (or possibly "GPIB Status" VI), and wait for my (NON-controller) i/f to be addressed.

"SendDataBytes" VI to respond.

The problem I am stuck on at the moment, is that I cannot find a way to determine which Subaddress was addressed, when "Wait" or "GPIB Status" indicates Talker Active state.

Thanks for any help or suggestions!

[DiegoF]

Hi Dave,

This question is not LabVIEW RT specific. I would be better to post it in the GPIB discussion group and see if any enthusiast (There are a few) has any suggestions.

BTW, I'm also looking into some alternatives.

DiegoF.
National Instruments

[Dave_Bell]

Thanks, Diego - I will do that immediately. And I greatly appreciate the continued help and suggestions!

[Sherwin1]

Diego, since your last note to me through the Forum, NI has been attempting to resolve our problem with GPIB Secondary Addressing. Were you involved in writing the latest extaddr.dll we were given? If so, would it be possible for us to discuss the software more directly? So far, we have been unable to get it to work in our environment.

Thanks!

Dave.Bell@LMCO.com