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Scan Lists for PXI-2532.

I have a switch (PXI-2532) set up as an 8x64 1 wire matrix.  45 pins of the DUT (columns) will be active, biased by 3 or 4 of the rows.  For a measurement, I will make a measurement on a pin using two columns while the biases to the other 44 pins remain applied.  In other words, can you set certain relays in a switch matrix  and leave them in a constant state while scanning (LabVIEW) other relays?

If I have to have a scan command that addresses all the relays being used for each scan, do the relays that aren't changing state remain in the same state while going from scan to scan or do they get reset for each scan regardless of whether they change states or not?
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Hi BWDW,

If you look at the niSwitch Configure Scan List.vi, there is a scan mode input.  The scan mode affects how the driver interprets the scan list. Typical scanning applications use the default Break Before Make scan mode.  In this scan mode, connections from the previous scan list entry are automatically disconnected before executing the current scan list entry. Disconnect actions, such as ~r0->c0, are not valid in this mode.

You want to use the No Action scan mode.  In this scan mode, connections remain connected until they are explicitly disconnected by a disconnect action. 

To answer your first question directly, you can set certain relays in a switch matrix and leave them in a constant state while scanning other relays.  You just need to change the default scan mode from Break Before Make to No Action. 

As for your second question, in Break Before Make scan mode, I believe even if the relays aren't changing state between scans, they would still be reset.  However, this should not cause an issue, as you need only use the No Action scan mode in order to specify which disconnects to perform. 

Let me know if you have further questions or if this does not resolve your issue!

Chad Erickson
Switch Product Support Engineer
NI - USA

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