Hi Andy,
You can adjust the rates in software by changing the scan rate in a loop or you can use "switch cycle" as a counter application by switching the frequency in a loop. But both of these are software timed and can be inaccurate because of the timing of the operating system as it runs your program.
The best way to do this is to sample your data at your cards fastest rate and then ignore samples to achieve the rate you are looking for in the given period of time.
For example, if you have to sample at 5kHz and 10kHz you can just sample all data at 10kHz and for the samples you needed at the 5kHz rate you can ignore every second sample but then include all samples for the phase in which you need to sample at 10kHz.
Obviously, this won't workout
perfectly in less you have a lowest common multiple of each of the frequencies you need and less than the sampling rate of the card. However, you should only be off by roughly +/-100 Hz.
If the timing interval 5ms is less important then getting the exact sampling rate then use the software methods mentioned above. Otherwise use the fastest sampling rate of your board and remove samples from your acquisition to get the rates. Hope that helps.
Ron
