My NI Switch Module Does Not Make Connections and Gives No Errors

Updated Jun 1, 2018

Reported In

Hardware

  • PXI-2530
  • PXI-2530B

Driver

  • NI-SWITCH

Issue Details


When I run a program that uses a PXI or SCXI Switch, everything seems to run fine with no errors. However, when I check my connections for continuity, the connections are not made. Why is there such a discrepancy?

Solution

  • Check the Motherboard/Daughterboard ribbon cable
Some switch modules use a ribbon cable to connect the switch's motherboard and daughterboard together (See Image 1). Some modules have two daughterboards, each having their own ribbon cable which connects to the motherboard. Sometimes these cables get jarred loose when the board is handled. When these cables are disconnected, the behavior mentioned above occurs. Verify that the ribbon cables between the motherboard and daughterboards are secured by the cable latches.

Image 1. Ribbon Cable Connecting Motherboard to Daughterboard
  • Replace the relays
This behavior could also be caused by relays reaching the end of their lifecycle. Replacing the relays could fix this issue. 
  • Reinstall the driver
  • Reset the max configuration

Additional Information

The motherboard handles the software switch commands and then passes the commands to the daugtherboard, which houses the physical switches. Therefore when these ribbon cables become loose the switch commands are executed in software without any errors, but switches do not physically connect. Make sure power is off before attempting to reconnect a ribbon cable.

Some relay types physically connect and disconnect to perform the switch action. The mechanical movements wear out the relays over time and can cause the relay to no longer close or open. The errors returned by the software detect any problems with getting the command to the relay, but do not catch physical failures at the relay itself. This is why we track the relay life using the Get Relay Count.vi.
 

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