using labview to control multiple instruments

[goatdemon]

Hello, I'm trying to control multiple instruments with labview. First I'll be using a signal generator and a digital multimeter. Later I'll add other instruments like a lock-in amplifier.  I've been able to control the DMM and the signal generator independently by using the respective drivers and examples, but I can't find any examples showing how to operate both instruments at the same time. I want to generate a signal, then observe it.

I've cut and pasted the afore mentioned exampes together and ran them in a single VI. It works, but the timing seems to be off (it takes a while for the DMM to update).  In these examples the Signal is updated once, but the DMM looks for a signal continuously.

I just want to know how to control the timing of these instruments,  (signal updates, then the DMM looks for the signal) and any other pertinent information that may come up in the future.  Can someone point me in the right direction with an example or a tutorial?

-Thanks

--Matt

[mikeporter]

Could you post either your code - or perhaps a screen shot - of it. It's hard to say what might be going on based on what you said.

Mike...

[goatdemon]

Hello, I've attached a screen shot of my circuit. How do I post pictures on this forum?

-Matt

[Dennis_Knutson]

I think you have to understand LabVIEW a bit better. You have a scope (NOT a DMM) acquisition inside a while loop so of course it's updated continuously and since the signal generator code is outside the loop, it will only run once. You need to use dataflow (i.e. the error in/error out connections to control execution flow. If you want to continuously update the signal gen and the scope, place both in the while loop and if you want code for the signal gen to run first, connect the error out of the signal gen to the error in of the scope.