PXI

[phx_tech]

Hi,

I am new to Labview and would appreciate some help with the PXI 2530.  

 I am using a PXI 2530 switch matrix. And I am trying to do a four wire measurement.I tried doing this in two ways:

METHOD 1: I used the switch in the 1-wire 4X32 configuration and noticed that the time it take to close relays r0 --> c0 , r1---> c1, r2---->c2 and r3 ---> c3 is 2 ms. By closing these fours sets of relays I am doing a four wire measurement in which r0 is Force+, r1 is Sense + , r2 is Force -, r3 is sense negative.

Method 2 : I used the switch in 2 wire 4x16 configuration and noticed that the time it takes to close the relays r0--->c0 and r1--->c1 is 6 ms.

Why is the two wire measurement taking a longer time than the 1 wire measurement. I am ideally doing the same thing in both the configuration. I have attached my program  for reference. Please let me know if there is some way by which I can configure the switch as 2 wire and get the same measurement time as 1 wire.

[Tommy_G]

Hi phx_tech,

Is the time difference you are seeing when using the different topologies with your PXI-2530 consistent? In your VI when you are calculating the time it takes to perform the switching tasks could you run the different topologies more than once, for instance 500 times or so, so we can see the average time difference between the different topologies and make sure they are consistent?

Regards,

[phx_tech]

Hi Tommy,

  The time difference between the two topologies is consistent. I tried out the two different toplogy in my actual application which invloves measuring the voltage and current across a device .For this purpose I am using a PXI 4132 and DIO PXI 6533 . In this application we run the same topology repeatedly say a hundred times. When I did this the 2 wire topology takes a longer time than 1 wire. The average switching time for 1 wire was 2 ms and for the 2 wire was 6 ms

[Tommy_G]

Hi phx_tech,

Could you try to run the VI I have attached to see if you are still getting the 1-wire topology to run faster than the 2-wire topology? I ran the code here and was having the 2-wire run faster than the 1-wire topology.

Regards,

[phx_tech]

Hi Tommy,

  I ran the VI you have attached and my timings are 212 ms for 1 wire config and 465 ms for the two wire. My system configuration is Inte l core 2 duo processor and 4 GB ram.

[Tommy_G]

Hi phx_tech,

What you are seeing for the results is unexpected behavior. I have tested this code with a simulated PXI-2530 and also with a real PXI-2530 device in a chassis and observed the 2-wire topology to always run faster than the 1-wire topology. Did you change anything else in the code I attached other than the instrument handle? Also another quick question, are you using a PXI-2530 or are you using a PXI-2530B?

Regards,

[phx_tech]

Hi Tommy,

  I am using PXI 2530 with NI TB 2631. My chassis is a PXI 1033. I just ran the same code that you had sent . The only change that I did was change the instrument handle.

[Tommy_G]

Hi phx_tech,

Are you running any other programs while running this test? Also, have you had any issues with this card in the past or has it just started to show this behavior?

Regards,

[phx_tech]

Hi Tommy,

  I am not running any other program while using this. Also, The terminal box that i have now is a loaner that I got from NI. I have a pxi 4132, pxi 2530 and a pxi 6533 dio in my pxi 1033 chassis

[Tommy_G]

Hi phx_tech,

It seems as if the behavior you are seeing could be incorrect, but the software timing of how long it takes to complete the switch is not specified as a specific time since it relies on different variables for each case. You could always send in your board for RMA if you think it is something to do with the specific board, but there could be a chance that it would come back as no trouble found. If it came back as no trouble found, you would always have the option to perform more troubleshooting on the card if you wanted to. Let me know if you have any additional questions.

Regards,