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Nulling cDAQ 9237 gives Error -50150



I’ve been fighting an issue nulling the cDAQ 9237 module in LabView. I have created a task in MAX with five “custom voltage with excitation” full bridge transducers wired sequentially over two modules. I want to call this task into LabView and select one or more of the channels to null.


The attached vi is a modified version of the NI example “Acq Wheatstone Bridge Samples – NI”. Instead of creating the channels in LabView, I use the MAX task. This vi works as long as all the channels in the task are on a single module. I choose the task and identify the channels to null by name and it nulls just those channels. As soon as the task includes a channel from a second module however  Error -50150 pops up. I've validated the bridges and tried different channel combinations with no success. Any idea how to resolve this?


Additional info: I’m running LabView 8.2.1 and DAQmx 8.6. I’ve attached the vi and a series of screen shots to illustrate the problem.



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Hi jwsx,

Thank you for reporting the error and for providing such detailed information.  I saw the same behavior running the code in LabVIEW 8.5.  However, it appears that error -50150 only occurs if the channels wired to "DAQmx Perform Bridge Offset Nulling" are located on only one of the two modules.  For example, nulling Ch 1 and Ch 3 produces the error, as does nulling Ch 5 independently.  If Ch 1 and Ch 5 are selected together, there is no error.  This was reported to R&D (# 4HDABJ0O) for further investigation. 

As a workaround, select at least one channel from each module to null or create separate tasks for each module.  Leaving the "channels" input unwired is another option since this will default to calibrating each of the channels in the task.  Hopefully one of these solutions will work for your application. 

Jennifer R.
National Instruments
Applications Engineer
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