Determining if sensor is overrange or open

[LabViewer35242]

Has anyone written code to determine if any of their sensors are overrange or open? Most vibration analyzers on the market have LED lights on the hardware to show that a channel is overrange or open.  I guess that is some of the reason National Instruments bought IOtech a couple years ago.  My code is not broken into separate producer and consumer loops using queues, and I was debating whether to do the Overrange/Open check before DAQ or inside my DAQ loop incase a sensor goes bad.

[preston_johnson]

Some of the NI DSA hardware has open short detection built in.  What NI DSA hardware are you using?

[LabViewer35242]

8109 controllers with 4472B and 4462 modules

[Josh_B1]

Hi LabViewer,

Here a a link to the NI Dynamic Signal Acquisition manual.

http://www.ni.com/pdf/manuals/371235h.pdf

According to this manual, page , the NI 449x has per channel open an short detect. The 446x series, page A-10, has pre-digitization and post-digitization overload detection. The 447x series, page A-22, has postdigitization digital overload detection only. Starting on page 2-5 the manual details how to uses these features in LabVIEW using DAQmx Read property nodes. Please let me know if you have any additional questions.

Regards,

Josh B

[LabViewer35242]

Josh that is helpful but with the 4472s and 4462s it sounds like there isn't channel "open" detect in the hardware.  So, I guess I'll have to do it in code. The only way I can think to do it is by DC coupling the accelerometer since you can read a DC voltage (~11V) if the accel is working and then if it is open the DC will go to ~22V. I'd have to do this check initially before I go into my normal DAQ process where I AC couple the channels.

[Kyle_K]

You are correct, there is no "open" detect in the hardware. The explination you provided should work as long as you know what the expected voltage should be for a functioning circuit versus an open one. 

Kyle K.