Sample rate on cRIO

[NickBl]

I have a cRIO-9068 and in my program there is a while loop with case structures that will determine if a channel is on or off. I want to be able to control different sampling rates for the multiple channels that are open and reading data. If I have multiple channels on and reading data can I control different sampling rates simultaneously or does the wait until next multiple function control it for all the channels?

[crossrulz]

Are you using the FPGA?  If so, then the loop rate of the FPGA determines the sample rate.  If not, then you are using the Scan Engine.  The sample rate is determined by the Scan Engine rate, which is configurable in the project.  The Scan Engine does not do well with a rate under 10ms; you may get away with 1ms.

[NickBl]

Oh ok. I'm doing scan engine currently. So the only way for the sample rate to be different than other sensors is to have another cRIO chassis at a different scan engine rate?

[crossrulz · Accepted solution]

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@NickBl wrote:

Oh ok. I'm doing scan engine currently. So the only way for the sample rate to be different than other sensors is to have another cRIO chassis at a different scan engine rate?

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If you want to continue to use the Scan Engine for the sampling, that is correct.  You could also use hybrid mode with the cRIO where some modules are controlled by the FPGA and others use the Scan Engine or just do it all with the FPGA.  But then you will have to program the FPGA to do what you want.

[NickBl]

Ok thank you.

[NickBl]

Do you know the maximum sampling rate of the FPGA mode if I decide to do a hybrid mode?

[crossrulz]

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@NickBl wrote:

Do you know the maximum sampling rate of the FPGA mode if I decide to do a hybrid mode?

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That would depend on your module.  Read the manuals carefully as there are often specific sample rates the modules can sample at.