Need further assistance on SR# 7293500

[SteveBr]

Adam,

Thank you for your assistance so far.

Since receiving the new SMB 120 Attenuator cables, I have tried the following:

Changing the range on both AC and DC coupling to small amounts.

Changing the sensitivity on both AC and DC coupling.

Plugging into another channel on the 4472 card (along with changing the channel in DAQ assistant).

Going back to one of the old cables (which allow a ±10 V signal), which did work correctly.

Tried both of the new cables, both of which are working according to the DMM.

After doing all of these, the new cables simply give me a small signal on the AC coupling, and nothing on DC coupling.

Any advice is greatly appreciated.

Thanks again,

Steve

[enderWiggin10 · Accepted solution]

Hi Steve,

I just caught this on the forums.  As we discussed over the phone,  I was able to get the cables to work on my end with the -10dB attenuation cables in both AC and DC, but we found the signal to be incorrect in your situation.  The cause of the problem was a high DC Bias Voltage from your sensor (8V) and then your signal was railing at the 10V input range of your PXI-4472.  We could not use AC coupling because the Time Constant of the AC coupler was too fast for your setup.  We were able to get everything working by using a PXI-4462 in DC coupling mode with a +/-42.2 volt input range.  Thank you for following up and let us know if this setup ends up working for you.

Best,

[SteveBr]

Thanks again for your help Adam.  I had posted this before we spoke over the phone and hadn't gotten back on to say the problem was solved yet.  The 4462 card is working much better for this application.