Connect Multiple Channels of a Multiplexer at the Same Time in LabVIEW

Updated Sep 11, 2018

Reported In

Hardware

  • PXI Multiplexer Switch Module
  • PXI-2527
  • PXIe-2527
  • PXIe-2525
  • PXI-2530
  • PXI-2530B

Software

  • LabVIEW

Driver

  • NI-SWITCH

Issue Details

I have a multiplexer switch module I want to connect multiple channels or run scans on different channel groups at the same time in LabVIEW.

Solution

This can be done as long as the following conditions apply:
 
  • The card must have multiple banks.
  • The channels must be in different banks.
  • The selected topology uses the banks independently.
For example, the PXIe-2527 only supports one simultaneous connection using the 2-Wire 32x1 Mux topology because all channels share com0, but the 2-Wire Dual 16x1 Mux topology divides the cards in two independent banks, one connecting channels 0 to 15 to com0 and the other connecting channels 16 to 31 to com1, hence allowing two simultaneous connections, connecting one channel of each bank to its corresponding com terminal.

For example, you can connect ch0 to com0 and ch16 to com1 at the same time, but not ch0 and ch1 to com0.

Refer to NI-SWITCH Programming Examples in the NI-SWITCH Help to find the niSwitch Making Connections on a Switch example to learn how to implement individual connections on channels in different banks using the niSwitch Connect Channels VI.

If you want to run multiple scans, you can similarly scan through the channels on each bank at the same time, specifying the connections in the Scan List. For example, you can setup a scan to go through channels 0 to 4 and 16 to 20, connecting them to their corresponding com terminal in a one-by-one fashion, specifying the following scan list:

ch0->com0&ch16->com1; 
ch1->com0&ch17->com1; 
ch2->com0&ch18->com1; 
ch3->com0&ch19->com1;
ch4->com0&ch20->com1; 


Refer to Scan Lists in the NI-SWITCH Help to learn about the scan list syntax and to the NI-SWITCH Programming Examples to find the niSwitch Software Scanning, niSwitch DMM Switch Synchronous Scanning and niSwitch DMM Switch Handshaking examples to learn about different scanning implementations using National Instruments Multiplexer Switch Modules.

Additional Information

Scanning operations can be programmed to switch channels based on a software trigger, an external trigger or using handshaking for improved synchronization. Refer to the NI-SWITCH Help to learn about the different trigger schemes for Scanning and to the NI-SWITCH Programming Examples to learn how to implement them.

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