Options of NI DAQ products to measure resistance for continuity tests

[sharp]

Hello,

I am new to DAQ and I was doing some research. Basically, continuinity tests have to be performed on a switch (note: I know the manufacturer performs their own tests to determine contact life cycle, but we need to test it in a modified environment).

Available to us, is an automated machine that can test switches, a mechanical arm that can push down at various speeds. Rather than manually doing this with a digital multimeter (eg. beeps), to check every couple thousand presses, we would like to automate the test and record the log onto the computer. So, it isn't a continuous log, but rather a periodical measurement of resistance (likely in milliohms if lead resistance is eliminated) which will confirm that switch is functional. And this log would eventually be converted to an excel spreadsheet for easy view.

I did a quick search without restricting it to PCI, for resistance measurement in "Data Acquisition" products of NI, and there is a USB solution (NI 9219) which is about $1500 + $labview. It is a bit pricey but it seems the H/W side of it is relatively easy wire set-up, unsure if it would be difficult with labview to tell it to read measurements once in a while and then write the log to an excel file.

However, Are there significantly cheaper PCI card (digital - direct or indirect resistance measurements using voltage/current) solutions to the type of measurement I described above? Will there be extensive programming involved?

I am open to alternate methods if you believe there are more effective ways to perform the continuity test.

Thanks.

[johnsold]

How many switches will you be testing simultaneously? 

My suggestion would be to simply provide a power source (5 V from the DAQ device unless the switch test requires higher voltages or currents) and a resistor to limit the current. Then measure the voltage across the contacts when the switch not pressed and again when it is pressed.The voltage should be about 5 V when open and mV or less when closed. You could do this with any analog input device with suitable input ranges and number of channels.

Of course you also need to measure or get a control signal from the mechanical actuator to know when to take readings.

Lynn

[Dennis_Knutson]

Instead of taking a voltage reading, you could also use digital inputs if you are only concerned with the switch is open or closed.

Programming resistance, voltage, or digital measurements of this type is not terribly difficult and you can use languages other than LabVIEW. What are you most familiar with?

[JefeL]

As mentioned above there are many ways we can accomplish this with many of the products we offer. Please call our support line at 1-866-275-6964 and one of our Applications Engineers can help you with specifications and product selection. You can also call 1-866-337-8760 and speak with an Account Representative who will also help with product selection and help you with pricing.