Digital I/O

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Connecting 36VDC to a Digital I/O device. Signal conditioning ideas

I'm making a test jig and I have about 32 output signals to check, they are all either 0-12VDC outputs or 0-36VDC outputs, I don't need to necessarily read their values (analog read), I just need to see that they turn on and off (digital). 


I thought this would be a perfect fit for a simple digital I/O device like this.


But it has a max input voltage of 5VDC.  Some of my signals are 36VDC.


I found these




But looks like I'm stuck for the 36VDC level because they only work up to 28VDC.


There has got to be a cheap way to bring all these outputs down from 0-36VDC to 0-5VDC.  I'd prefer not to make a custom board, but if I have to I will.  I would also entertain a large Analog input device that could read all these inputs and their voltages, but I have a feeling that would be VERY expensive to find a 32 point analog input card (>>$2K)


Any ideas?


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I would probably go with a cDAQ chassis (for example cDAQ-9174) with a mix of NI-9425 (32x 12V or 24V digital inputs) and NI-9437 (8x 24V to 250V digital inputs) modules.  Then it is direct wiring into your module.  But this is probably more than you want to spend, but you will spend a lot more in your labor by the time you come up with a better solution.

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If your signal rates (frequencies) are not too high you might consider an industrial optocoupler module. Murrelectronic of Germany makes optocouplers accepting anything between 10 and 53V dc on the input. The drawback: they need about 10mA for switching (since you have to drive an input LED directly).


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