Error -200077 while setting up task in MAX

[Seaman008]

I'm creating an AI task with MAX that scans channels ai1-ai9 of a mseries daq.  The input range is -10V to +10V.  It's all fine until I attached each channel to a custom scale within MAX.  It appears that the input range of each channel is dependent on the scaling somehow.  For example, when I set the slope of a scale to 0.5, I will get the error -200077 from MAX when trying to save the AI task.  The err message says the valid range is now 5V for the channel to which the 0.5 scaling applies.  I could save the task only after changing the input range to +/-5V as MAX demanded.  Similarly, if the slope is 0.2, MAX wants the input range to be 2V.

Does anyone know what is going on here?  I really don't understand the dependency between the input range and the scaling factor here.

I have Ni-DAQmx 8.50.

S.

[RavensFan]

Yes.  The input ranges are a function of the input channel as well as the scaling factors applied.

[Seaman008]

I'm still puzzled by this behavior.  So if my input has a dynamic range of +/-10 and I need to scale it down by 0.5 to get the proper unit for display, for example, then I can't use custom scaling within an AI task to do it?  That would mean my VI has to scale the samples after getting the unscaled readings, but NI-DAQmx won't be able to do it for me.  Is that true?

S.

[RavensFan]

Only 3 stars?  Come on.  Just because the setting is puzzling doesn't make the answer bad.

You can use custom scaling in the task within MAX.  But once you set the scaling factors, the range becomes units of the scaling as opposed to the raw units of the input.  So you have to adjust the min and max values of the range to reflect the converted units.

I set up a 30,000 lb load cell to be read by my SC-2345 chassis.  Attached is a screen shot of the setup in Max.  Since 2000 microstrain (or 2e-3 strain) is the basis of a 30,000 lb load, I had to make my slope of my scale 15 e6 lbs to get the correct values.  My default input range was 1m to -1m.  I found that the readings pinned out at about 500 lbs when I did that.  So I made the input range 30,000 to -30,000 lbs and the load read correctly in the test screens within Max.

See the attached screenshot showing the setup in Max.

I made a simple VI that uses the DAQmx read function with that task as the input.  The indicator read the load correctly.

[Seaman008]

Hey, I think I was being generous to give 3 stars for the 1st answer, man 🙂  But the follow up is much better so I gave it 5.  Thanks!

S.