Different sampling behavior with different CDAQ chassis

[AmandaBacala]

I am setting up a strain gauge measurement and right now I have a full bridge set up made entirely of resistors, just to verify my test set-up. I have been using a 9219 module with a 9171 chassis and I have been able to get the sampling behavior I want using these parts. My sample frequency is 20S/s and I get 20 distinct samples per second using this set-up (measuring V/V).

I also have a 9174 chassis that I would like to use instead so I can incorporate other measurements. For some reason, just switching out the chassis and using the exact same LabVIEW code results in different behavior. This is the data I get with the 9174 (same module):

So, technically it is giving me 20 data points per second but I have no idea why the values aren't changing every sample. My understanding is that the sample rate the DAQ is capable of is dependent on the module, not the chassis -- so why would changing out the chassis result in this change in behavior?

If anyone has any ideas here, they would be greatly appreciated. Thank you!

[AmandaBacala · Accepted solution]

Figured it out -- apparently I had the timing mode of the device set properly for the 9171 and not the 9174. I added a property node to the LabVIEW code to set the timing mode to High Speed (image attached) so I believe this would fix the issue for any new chassis. I am now getting 20 distinct samples per second with both chassis.