PXI-2503 scan list

[m@NI_forum]

I have a PXI-2503 multiplexer with a TB-2605 Terminal Block and need to scan channels 0:9 using "2503/4-Wire 12x1 Mux" topology. When I measure resistance with Keithley 2400 connected to com0 terminals of a multiplexer everything works just fine. I use the ch0:9->com0; scan list string.

Now I'm trying to measure resistance with a PXI-4072 DMM instead of Keithley 2400 and have a problem with a scan list. I need to connect com0 and ai0 (checked in MAX and it works), but I cannot find the right format of a scan list string to do that. Can anyone help me with that please?

It looks like ai0 is invalid terminal name.

[AJost]

Hi M,

IMHO, the scan list should still be ch0:9->com0 regardless of the DMM you are using.

But instead of connecting the Keithley 2400 do the same connections to the PXI-4072 DMM.

There are no internal wirings in the chassis for analog signals (and to be honest, you don't want to run your analog signals via the backplane of the chassis), so all the wiring betweeen the switch and the DMM needs to be external.

I hope that answers your question,

Andreas

[m@NI_forum]

Andreas, thanks for your reply. You are right, with DMM I can use the same connections as I used with Keithley 2400 and it should work. I just want to make use of a Analog Bus Connector on TB-2605 terminal block shown on an attached photo and schemes (item 9 on TB-2605.jpg). 

[AJost · Accepted solution]

Ah, now I understand where your question was aiming at. It should be ab0 instead.

I don't have a 2503 at hand to try things out but according to the schematic in the attachment, you want to have com0->ab0 closed the whole time.

Thus, I wouldn't include this connection in the scan list (it's purpose is scanning), but use a NI switch Connect Channels vi before your measurement to connect com0 and ab0 (and disconnect afterwards). Then just use the ch0:9->com0 as scan list.

[m@NI_forum]

Thank you, Andreas. It turns out that I just haven't noticed that terminal name is ab0, not ai0. And thanks for the advice regarding Connect Channels vi. That makes sense.