Connection diagram NI 9208

[AndreyElx]

Hi!

I connected a loop-powered 4-20mA transducer as suggested at the page 13 of the NI 9208 guide. Particularly, an external supply is connected to Vsup and COM and the transducer is connected to Vsup and AI0. But in LabVIEW the DAQ assistant shows me a different connection diagram. It's suggested to connect the transducer to AI0 and COM. Should I just ignore the connection diagram in DAQ assistant? Is it supposed it works correctly even the connection diagram wrong? I'm asking because it's difficult to check a setup directly since the transducer is a gas detection device and there is no data about actual gas concentration. Thanks!

[oscarfonseca · Accepted solution]

My advice would be to follow what the device's specification sheet says.

In this case, since the Shunt Resistor is between the AI port and the COM port, I would expect the load to be between the Vsup and AI ports.

[AndreyElx · Accepted solution]

Thanks for your answer, Oscar! Yes, as I wrote I connected the sensor to Vsup and AI as proposed by spec. My question was slighly different. I was worried about let's say reliability of readings obtained in LabVIEW because in LabVIEW the DAQ assistant expects a load connected between AI and COM.
I could not affect on the sensor's input to check the behavior of readings. Then I just replaced the sensor with different resistors and seems everithing is fine. It was just a bit confusing to me.