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Expose total number of channels (including cold-junction and autozero) for thermocouple devices in software

Status: New

Hello everybody!


Currently the AI.PhysicalChans property returns the number of physical channels for measurement (e.g. 16). However, to calculate the maximum sampling rate for the device programmatically (e.g. 9213), we need the total number of channels including the internal ones such as cold-junction and autozero (for 9213 it's 18).


Therefore I would like to suggest to include a property node with the number of the internal channels or the total number of physical channels or something similar.


Use case: programmatically calculate the maximum sampling rate in a program that should work for multiple types of devices without being aware of their type.


Thanks for consideration and have a great day!


[actually a customer's idea]

Zenon Kuder
Applications Engineering
National Instruments
1 Comment
Trusted Enthusiast

Hi Zenon,


Interesting idea.  One other approach would be to configure a task as you desire and then query the maximum rate through a DAQmx Property Node:





There are quite a few parameters that affect the maximum rate (for some hardware anyway), so rather than trying to calculate the rate yourself it might make more sense to let the driver do the work for you.  The downside is this requires you to actually configure a task.


I can still see other cases where one might want to know about the existence of the internal CJC and Auto-Zero channels through a DAQmx Device Property.

John Passiak