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Can you/should you read the same analogue input node in multiple places using the FPGA Module

Hi,

 

This may be a fundamental question, but can you or should you, read the same analogue input node from a CRIO module in multiple places in FPGA LV?

I.e in two separate sub VIs read the same AI?

 

 Best regards,

 

Si

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Hi Si,

 

you can read in multiple places.

 

The "should" boils down to "does it hurt your performance"? It has side effects to access the same module/port/channel in multiple places: you may not get the sample rate (or loop iteration time) you expect...

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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Reading a single point AI on an FPGA is pretty fast.  But it is much slower than reading from a variable.  So if you can read in a single loop with some kind of indicator that a new read has taken place (FIFO, or setting a boolean flag) then it probably would be a better design from a performance stand point.  But it does add complexity and if performance isn't an issue maybe the benefit isn't really worth it.

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Just to add to the answers...

 

AFAIK, Multiple nodes will read multiple times. So it's not the last value that is returned, each node acquire a new value. As mentioned, this could change the expected data rate, but it also means the values you read (potentially simultaneously) do not give the same value.

 


@SRML1124 wrote:

This may be a fundamental question,


Nothing wrong with that!

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