trigger problem in cwgpib

[tinypure]

Hi,

   I am using a CWGPIB control to interact with a HP spectrum analyzer. In the GPIB programming guide which comes with the intrument, it says writing a command "*TRG" should be able to trigger a measurement if the trigger source is set to be BUS. However when I used CWGPIB1.Write "*TRG", it didn't work. I tried CWGPIB1.Trigger too. Both of them didn't work. But if I used NI-488.2 commnicator to write string "*TRG", then it can successfully trigger a measurement. Do you know what's wrong and what I should do to trigger a measuremng using CWGPIB control. Thank you very much!

Regards,

xiaochun

[JLS]

Hello,

Interesting... well, it could be the default method of termination used by the CW control.  GPIB uses either the EOI line (asserted by the "talker" with the final byte of a transmission) or an EOS character (much like termination character reception is often used to terminate serial reads) to terminate a read operation.  Can you try configuring the CW control for EOI termination?  The NI-488.2 commnicator uses EOI termination by default, so unless you changed that (by clicking the configure EOS button) then your instrument likely expects "EOI-style" termination.

From a more practical standpoint, do you need to use the CW control?  VISA is another API which you may find an ocx control for; NI-VISA can communicate (indirectly by calling into NI-488.2) with your GPIB hardware, and you may find the defaults and/or the interface to that control more friendly.  Also, if you plan to do some programming, what language will you use?

In any event, definitely repost if you continue to have trouble, and we'll get to the bottom the issue!

Best Regards,

JLS