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NI DAQ channel terminal in MATLAB is read-only

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Hello, I am using an NI-9422 to read in a signal for motor speed. I am reading in through the data acquisition toolbox in MATLAB. I can read the frequency fine for 1 terminal but I am struggling to understand how to read multiple terminals or a specific terminal.
For instance, the current assigned terminal is PFI5 and if I try to assign a variable ch to my channel and then re-assign the ch.terminal as PFI7 it says it's read only. I've also unplugged, and plugged the chassis back in and the default terminal changes which I can only solve by moving my wires.
What am I missing? Thanks for any help.

Accepted Answer

Hyalex Ortho
Hyalex Ortho on 1 Mar 2023
I realized I need to change the 'ctr0'/'ctr1'/'ctr2' when adding the input. Device pinout on the NI MAX was helpful.

More Answers (1)

chrisw23 on 28 Feb 2023
As long as the PFI is configured as Input it should be readOnly.
Each PFI line can be individually configured as a static digital input or a static digital output.
Check the current I/O state.
Hyalex Ortho
Hyalex Ortho on 1 Mar 2023
I see, I am trying to read in more than 1 input, so how do I pull data in from the other PFI terminals? It seems to default me to PFI5 and I don't know when adding my input how to specify which terminal I'm reading in from. I'm not trying to change the name or write to it, just trying to access a different terminal.
chrisw23 on 1 Mar 2023
I'm not using the DataAcqToolbox but the DAQmx API instead but I think it is similar.
When you define the task you have to add all channels you want to use and you can't get access to a channel that is not defined for that task.
% physicalChannelName
% nameToAssignChannel (alias)
% enum NationalInstruments.DAQmx.AITerminalConfiguration
% minimumValue
% maximumValue
% NationalInstruments.DAQmx.AIVoltageUnits

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