回复： Trying to auto detect if my sensors are disconnected to our NI-5105 digitizer

[Hull-IQ]

We're using an NI-5105 digitizer that has 4 sensors connected to channels 0,1,2,3.  I would like to dynamically detect if 1 or more sensors goes bad or a connection is broken (disconnected).  There are many niScope objects in LabView and I have briefly looked at them all.  I can see there is an Auto Calibrate function, but I don't think I want to perpetually calibrate the scope.

Effectively, I need to be able to send a signal out of the scope and only if something is connected would it be echo'd back.  Otherwise, no echo would occur and I could safely assume that nothing is connected.  Alternatively, if there would be some way to detect a "load" on the input of the digitizer, and when the load disappears (goes infinite) or shorts out, then I could detect either case and display infor to the user.

I want to display a red icon of some sort when/if 1 or more of our sensors goes bad or a connection is broken.  I want to do this dynamically, so as the application is running, it would be giving continuous feedback as to the "health" of the sensors.  I don't want to have the user go to a Maintenance page to click a button to determine if the sensors are ok, but if that is all thats available, I at least want to do that.

I have tried to use the niScope Send Software Trigger Edge function, but when I attempted to use that, it gave me this error (-1074116060) "Specified operation can be performed only when the task is running.  Start the task before requesting the operation.  Status Code = -200475"

When I went online to find out more ab out this error, I could not bring up anything meaningful and there were several thousand hits for issues that didn't seeem connected to my problem.

Thanks,

[John_P1]

Hi Hull-IQ,

Welcome to the NI Forums!  You can export a digital signal on the PFI line of your 5105, but I am not sure how you could use this to check the status of your sensors.  If there is a way to have the sensors respond to a TTL pulse, then you could read this response on one of the open analog channels to see if the sensors are functioning properly.  Another possibility would be to display an indicator based on your analog input data itself--if it is within a certain threshhold of 0 volts then you could assume a short circuit (depending on your sensor).  Also, you could look into using external circuitry to detect the short.

The Send Software Edge function needs to be called after you start the niScope task, as the error message indicates.  This function will send the specified trigger to the digitizer, and is probably not what you want to use to output a signal to your sensors.  I hope that clears up the issue, but let me know if you have any questions.  Happy Holidays!

-John