Get readings from two dmm

[Mihaylov12]

Hello,

I want to make simultaneous measurements for Vac and Vdc with 2 DMMs (Agilent 34401A) with external trigger and then to log results in file. I made a simple state machine with 3 states:

-Initiate devices

-Triggering the dmms using NI USB-6008 and then read data from dmm external memory with fetch function and while loop

- Write results in .csv file

-Run this VI until it reaches measurement count.

I set trigger count to "1" and sample count to 100 but when I try to run this VI, timeout error occurs in Fetch function. The purpose of this large number of samples is to make more precise measurement. 

I tried to debug the program and found out that Vac measuring is a lot slower than Vdc measuring. If I set Vdc measurement for all DMM - then I dont have this timeout problem, but it my case I have to measure Vac and Vdc.

I have attached my project below - my main vi is stateMachine.vi

Thanks in advance!

[santo_13]

Of course, it will be slow as it is clearly mentioned in the instrument datasheet, if you need to synchronize them perfectly, you need to figure out settings for each that would match in measurement time.

[Mihaylov12]

Hello,

I set the sample count for Vac DMM only to 5(I don't need too many samples for this measurement), but now I face same problems- the error is ether timeout or -410 query interrupted. 

I cannot figure it out why fetch functions throws this errors.