continuity tester

[Raikar]

I am new user for Labview,my application is to build a complet fuctional tester,i need to test continuity for onseide  32 pin male connector other side is 32 pin female connector,one to one point continuity,i need your help to custmise the hardware as well as code,i decided to use NI USB-6211,And USB Switch matrix,is it right,help me to find right instrument.

[crossrulz]

Personally, I'd rather use a DMM such as the USB-4065.  Finding a USB switch module might be interesting.  And I found an Agilent module that does 4x8 2-wire.  And thoughts on moving to PXI?

Anyways, you need a matrix with at least 32 channels.  Connect the + side to one of the 32-pin connectors and the - side to the other 32-pin connector.  Via that matrix, connect the DMM to the channel you want to test and do a simple 2-wire resistance measurement.

[Dennis_Knutson]

If you had picked a DAQ device with 32 digital lines, you could skip the whole matrix and test continuity of all lines at once. What drove the decision for the 6211?

[crossrulz]

I see where Dennis is going with this, and it it a good idea.  But first a clearification.  Do you only need to test continuity or do you also need to check for shorts between pins?  If you do not have to look for shorts, then you can go with a USB-6218 which has 32 inputs.  Tie all of the pins of one connector to the +5V of the DAQ and the other connector goes to the various analog inputs of the DAQ.  Measure the voltage of all the channels on the DAQ.  If you have to check for shorts, well, then you are back to finding a switch matrix.

[Dennis_Knutson]

I was thinking the 6509 (I should have said 32 inputs and 32 outputs) and with that, you can also check for shorts. With a pull-up on the output, driving one end low and detecting a low at the other end will confirm continuity. If you alternate the signals (i.e. 10101 etc,) if you detect a 0 when you expect a 1, then adjacent pins are shorted. With two writes, you completely test for continuity and adjacent shorts. Quick and simple and much cheaper than the 6211.

[crossrulz · Accepted solution]

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@Dennis_Knutson wrote:

I was thinking the 6509 (I should have said 32 inputs and 32 outputs) and with that, you can also check for shorts. With a pull-up on the output, driving one end low and detecting a low at the other end will confirm continuity. If you alternate the signals (i.e. 10101 etc,) if you detect a 0 when you expect a 1, then adjacent pins are shorted. With two writes, you completely test for continuity and adjacent shorts. Quick and simple and much cheaper than the 6211.

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Ah, you are using DIO instead of AI.  That's ingenious!

[Dennis_Knutson]

My first job, many, many years ago, was programming a functional tester and that's how we did it then.

[SnowMule]

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@Dennis_Knutson wrote:

I was thinking the 6509 (I should have said 32 inputs and 32 outputs) and with that, you can also check for shorts. With a pull-up on the output, driving one end low and detecting a low at the other end will confirm continuity. If you alternate the signals (i.e. 10101 etc,) if you detect a 0 when you expect a 1, then adjacent pins are shorted. With two writes, you completely test for continuity and adjacent shorts. Quick and simple and much cheaper than the 6211.

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Not a bad idea, but it depends on the connector/pinouts.  A Mini-USB connector could have a short to odd-numbered pins, probably more likely than to an adjacent pin since 1 to 3 and 3 to 5 are closer together on the PCB and on the same row unlike 1 to 2, 2 to 3, etc. Ethernet's kind of the same way since the connector pinouts aren't 1:1.

If you've got the DIO, test each line independently.  You'll catch opens and shorts to any pin.

[Dennis_Knutson]

Which is why I said the 6509 and it's 96 dio. With 32 pins at each end, you need exactly 5 patterns to verify continuity and that no pins are shorted to any other.

FFFF 0000

FF00 FF00

F0F0 F0F0

AAAA AAAA

5555 5555

[AnalogKid2DigitalMan]

Dennis:

Is there a reference you can post as how to determine the bit patterns for such testing? I may have an application coming up for testing a 20 pin header assembly.

Thanks

-AK2DM