GPIB and DDE communication

[HoSk]

Hi
I have an old application involving GPIB and RS232 communication with several instruments. For GPIB I use the oldest 488.1 VI's. Everything, datacollecting, storing, etc, are done in separate parallel loops. There are also a DDE server in a separate loop to hold all collected data. We use it for distribution of data online to several networked connected computers. Excel is running on this clients for evaluation purposes. Recently I added possibility to use three new types of GPIB-instruments. Then I use VISA-routines. It works very well BUT the DDE server has turned very slow. Before it updates 200 channels of data in 1 s now it takes 60 seconds. When I changed VISA routines to GPIB 488.1 all is working perfectly, DDE is okay again. I thin
k this is strange, what have VISA to do with DDE? Do anyone have any clue? (LV 6.001 Win NT)

[Dan_Mondrik]

What might help is an NI Spy log. It will show how long each function invocation took, and whether there was any contention (eg, multiple calls coming from separate threads and/or applications, etc.). It will help us more if you use the Spy option to Log to File, and do not use the File>>Save menu item.

You could either attach the .spy file to this forum, or send it to NI technical support via email.

Dan Mondrik
National Instruments

[HoSk]

Hi
Please see enclosed NI spy log file. It's for a configured system with a HP-scanner with 488.1 routines and a Yokogawa with VISA routines. In the beginning there are some initialize commands and then the scanning begin. I also tried the profiler tool and it seems to not work with the DDE routines. I got the value 1844674407288 seconds for DDE Master Control.vi. But I only run the program for a few seconds. I also tested the DDE advise example from the example library together with the profiler. I didn't got any time values only # calls. Why?
Thanks for your time