Continuity testing with a PCI 6221

[Joe Beauchamp]

Hello, I was wondering if anyone has some advice about how to setup a continuity test using an M Series PCI 6221 DAQ and Labview 7.1. Specifically, I want to preform a testing regime similar to the IPC-SM-785 guidelines during thermo-cycling of the test vehicles. For those not familar with the guidelines, the purpose is to monitor the resistance of channels that have a DC (10V max.) current (2mA max.) running through them. If the resistance exceeds a certain threshold it is considered "an event", and if ten events happen in a specific time-frame the channel is considered to be "failed".

I am a relative new-commer to NI DAQs and the associated software, so any advice would be greatly appreciated.

[bushman]

One way of doing it is to use two analog input channels on your card. Use one to monitor the voltage the other to monitor the current. To monitor the current you will need to add a shunt resistor in series. Use Ohm's law to convert the voltage to the current. Monitor the signals and if you are at 2 ma and not at 10V you are in an error condtion. Tjis is assuming the power supply is a constant current, constant voltage source.

[Joe Beauchamp]

Thank you bushman, one thing that I forgot to mention is that I intended to use a multiplexer to get enough test channels (178 out of 256) for this test. Usinging this method I would need to have a pair of input channels (one for voltage, one for current) for each test channel, correct?

[bushman]

Yes you would