9215 voltage railing

[StevenHowell]

Hello I just bought a NI 9215 and I am testing and prototyping on the cDAQ 9172 while I wait for my 9075 to arrive. I also have the 9411 for reading in a TTL pulse coming from an anemometer. 

The 9215 is reading the following voltages

3  0-5VDC 

These signals each require a 5V excitation source which I am providing from the source lugs on the 9411 and feeding in 12VDC  to the power connector. 

I have everything wired correctly, on the 9411 and I am getting power to my sensors, however, when I run the test panels in the express DAQ assistant, I am seeing all 3 channels railing between -10 and 10....on my scaled units, the front panel all the readings are railing min to max....I tried connecting the AI- to the COM on all 3 channels and this did not help. 

Am I missing something? 

Thanks 

Steven

[Gregor Cerne]

Hello Steven,

Please try to connect power from NI 9411 module directly to NI 9215 module (COM to AI0- and +5V to AI0+) and tell we if you see 5V - to eliminate hardware problems.

Best regards,

Gregor Cerne

[StevenHowell]

thanks for the reply Gregor, I was looking again this morning, and believe I dont have a true ground reference, I am going to tie the COM terminal to building ground and see if that resolves the issue, also since my sensors are not providing much of a load to the signal, I may need to put resistors in line with the sensor to ground.