Simulate Loop Power with a NI 9265

[N1CO_M3]

Is simulating a loop-powered device possible with the NI 9265 like how I can do it with a FLUKE 789 Processmeter?

My objective is to simulate analog signals to validate instrumentation. I was able to simulate a 0ma-20ma signal with the NI 9265 card using an external power supply (12VDC). Are any suggestions on how to simulate a loop power device (i.e. 2-wire device) where the excitation voltage at 24VDC is supplied in line? In other words, I don’t want to use an external power supply, but the supplied voltage by the 2-wire to drive the NI 9265.

[Jorr-El]

Hi N1CO_M3,

A few questions:

1.   Are you using a chassis with your NI 9265? Which chassis are you using? Or, are you trying to power it without the chassis?

2.   What are you trying to accomplish with your NI 9265 that requires you to do this (provide the excitation voltage in line)?

3.   Are you using a controller to simulate the analog outputs through your 9265, or how are you controlling the 9265?

[N1CO_M3]

Thanks for the reply.

1.   Are you using a chassis with your NI 9265? Which chassis are you using? Or, are you trying to power it without the chassis?

 Yes, the cDAS-9188. No, I'm not trying to power it without a chassis.

2.   What are you trying to accomplish with your NI 9265 that requires you to do this (provide the excitation voltage in line)?

There are several sensors that are loop powered. For example, a pressure transducer can be loop powered. This allows you to only run a 2-wire cable to the transducer from your DAQ system. That way you don't need an external power supply to power your transducer (hence, excitation is inline).

I'm trying to simulate an analog signal with the NI 9265 (in other words, simulate transducers). I can simulate 0-20ma the NI 9265 and I can simulate +/- 10V with the NI 9263. My question is can I simulate a loop powered device (4-20ma) with the NI 9265 or a different card?

The objective is to validate a DAQ system. Normally, we have a FLUKE 789 to validate/calibrate the loop powered systems. I figured that if we have a DAQ system with numerous channels, we can easily/quickly validate the system using a chassis and NI 9265 cards. (instead of taking the fluke an going one by one to each channel can validating the channel).

3.   Are you using a controller to simulate the analog outputs through your 9265, or how are you controlling the 9265?

Yes, with a labview program.