Can I configure a only channel like measurement Period?

[juanpedro14]

Hello Everybody,

I am working with NI 9421 module. This module is a digital input. I configured  a channel like measurement of period. My problem is that when I configure a channel like measurement of period  all the channel change  their  configuration and I need that the others channel are working like digital input.

Any ideas will be very helful.

Thank you.

A regard

Pedro

[GerdW]

Hi Pedro,

where do you plug this module in?

How do you configure the module?

When you use the module in a cRIO with the help of the ScanEngine you are quite limited. Even when you can configure several different functions the all apply to all inputs…

[juanpedro14]

Hello GrdW,

Thank you for your help. I have pluged this module in a CompactRIO 9035 and I am using ScanEngine and I try to configure this module in his properties ( I click right in this module and I go to properties and specialty digital configuration). I don not know if it could configure a channel like measurement period when I am using ScanEngine.

Thank you.

A regard

Pedro

[crossrulz · Accepted solution]

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@juanpedro14 wrote: I don not know if it could configure a channel like measurement period when I am using ScanEngine.

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I am fairly certain you cannot.  But the joy of a cRIO is that you can define your interface by writing your own FPGA.  You can even use "Hybrid Mode" which will allow you to use the Scan Engine on certain modules and the FPGA on others.  For this digital module, you will need to write you own FPGA to measure the period.

[juanpedro14]

Hello Everybody,

I am working with NI 9421 that is connected on CompactRIO 9035. I am reading a digital signal of proximity sensor. I want to read of period between two pulses. I want to know rpm of a wheel. I attached the program what I did it. 

I try to read of period with tick time but I have really problems speed of the loop because if the loop is too faster I don´t read very well. I am using ScaneEngine. I made this program because if I configure the NI 9421 like period measurement changes all the input and I need other inputs of this module to read other signals.

Thank you so much.

Any suggestion it will very helpful 

A regard 

Pedro

A

[GerdW]

Hi Pedro,

I moved your message because basically you already got the answer you asked for!

Please don't create double posts on the very same problem!

You have two options:

- Increase loop rate to 1kHz to allow upto (theoretically) 500Hz puls rate measurement

- Use the FPGA to program each DIO pin individually

Btw.: You surely want to detect boolean crossings in your DI signal instead of just the TRUE level…