Hello,
I am writing an application in C# .NET using the DAQMX library, and I have 8 strain gauges I need to measure using two NI 9237 units connected by USB to my computer.
The problem I am experiencing is that the timestamps of the samples read by the two units seem to differ slightly from each other.
I could not measure both units in one task, so I created two tasks.
As a test I start both tasks and measure data for a few seconds. During this session I plant a solid kick in the mechanical structure that the strain gauges are mounted to.
When I look at the data recorded, I see that this kick is measured at different timestamps for the two tasks although the should be approximately the same.
I have not done anything to ensure they were synchronized, I just assumed they were - at least approximately, but I got deviations in over 160ms apart at 2kHz sample rate.
The NI 9237 uses an internal clock, I have read, so the question is:
Is it possible to synchronize the two units without any extra hardware, and how?
I have searched the forums and google, but most related info were that 9237 did not synchronize well with other units that uses external clocks as timebase because 9237 uses an internal clock.
