Time stamp bizarre issue

[GPGPR]

I'm using a PXI-6220 to acquire continous data synchronized with an external pulse.

System acquire data at the rate of the external pulse.

When a disconnect the external pulse input, data stop acquiring which is normal. When i reconnect the external timming source, data continues to acquire.

The problem is time stamp. If data stop acquiring 5 secondes so the time there were no timming source, the time stamp is late and give the next time increment related to the last time stamp acquired before it stop!?!?

I expected to get the actual time stamp after reconnecting the source...

Is i'm missing something?

[David L.]

Hi GPGPR,

The timestamp is according to the DAQmx read, hence when the sample clock stops, the chart and/or graph stop as well. If it is just your signal that stops, then a waveform chart will continue to graph, but it will be a blank signal until your signal returns. If it has to be your sample clock source which stops, than the only way to get a true time is to do this in software using the ‘get date/time in seconds.VI’. A typical specification is that the sample clock has to be a continuous and free-running clock for just this reason.