NI-9234 streams sometimes valid data, sometimes 0

[lsstpkubanek]

I have a simple application to readout data from NI-9234 modules, and display the values in indicators:

When I run this (on cRIO FPGA, under LabView), sometimes only 0 are readout and readout is a bit slow:

When stopped and run again, sometimes valid data appear:

I also noted that when data are updated and non-zero, the counter (Numeric indicator on the front panel) increases much faster.

I come to this as I am reading 0 in a more complex application, which stores data into FIFO. Any hint of what might be wrong? Why it sometimes works and sometimes doesn't - all I do to make it run is to stop the application and start it again.

[lsstpkubanek · Accepted solution]

The problem is most likely solved. The behavior was triggered by syncy=ing NI-9234 to the clock provided by NI-9469 time synchronization module. When synced to NI-9234 clocks, non-zero data are readout all the time as expected.