Dear NI experts,
We are using a NI PXI measurement device, containing
1x PXI5404 main clock generator, which puts the clock on the PXI star line.
2x PCI5122 100MHz scopes
2x PXI5421 100MHz digiboards
1xPXI5421 100MHz AWG
1x PXI7831R FPGA card
The digiboards and AWG are running in one LabView loop, and are synchronized to the PXI star line using the TClk mechanism. This has been verified on external scope: all generated signals remain fixed relative to each other.
The problem is with the scopes. These are initialized to use the PXI star line clock with a fixed divider as clock base. This is specified through a "niScope" Property node having 3 entries, as shown in the "niScope EX Multi-Device External Clocking (TClk).vi" example.
At a fixed interval, one of the digiboards generates a pulse on the RTSI3 channel, which is used as digital edge trigger for both scopes. This works fine: the scopes start sampling after each generated pulse. But the delay between this pulse and the first sample is not fixed!
Why is this? Since both the device that generates the pulse and the scopes are running on the same clock...
Any help on this, or things to measure/try out would be appreciated a lot.
Kind regards,
Riemer Grootjans
Vrije Universiteit Brussel
