session based daq interface+usb-6218 shows drift

i'm using matlab 2011b together with the daq toolbox (session-based interface) and a NI 6218 usb-daq to acquire data from a six axis load cell.

all channels seem to work properly according to measurement and automatation. also i have used the same setup and code successfully with a pci-6225.

the measurement shows a strange drift (without applying any load) when measuring (compare figure: http://imageshack.us/photo/my-images/196/problemsdaq.jpg/). though they react on applied load. is there anything i need to change or some other known issues with the usb-6218?

thank you,

richard

Answer 1

[Walter Roberson]

There was a question some months ago about drift when using the legacy interface; http://www.mathworks.com/matlabcentral/answers/24758-drift-in-data-acquisition-toolbox-legacy-interface

There was also a question about drift when using multiple clocks in a session-based interface: http://www.mathworks.com/matlabcentral/answers/24757-daq-session-based-input-is-it-possible-to-have-different-clocks-for-input-and-output

Answer 2

[Tobias]

Hi,

should the device work in single ended mode or in the differential mode? You need to determine that in your code. This could cause drifts.

Best Regards Tobi