Waveforms looks off in Chart vs Graph

[kidderj]

I realize the (2) cDAQ chassis and modules are not in sync...But when reading a waveform from a (one ni-9225 in each chassis) ni-9225 a0 input in cDAQ-9187 chassis #1 and in cDAQ-9187 chassis #2 the timing being displayed on a Chart vs A Graph waveforn when zoomed in (on the Chart) don't match up and if I zoom in alot I get a 3rd waveform showing up. See attached document.

[Chad_A]

Best guess:

Your two tasks aren't synchronized at all, so they don't start at the same time.  However, the waveform data type does contain a "t0" attribute that approximates when the task started. The chart indicator actually respects the two different t0's, but the graph indicator does not.

Since there is a phase shift in the chart, but not the graph, the t0's must be different from one another even though the tasks did really start at about the same time. So that means DAQmx's attempt to approximate when the task started is not very accurate for one or both of the tasks. Here's how DAQmx calculates t0: http://digital.ni.com/public.nsf/allkb/5D42CCB17A70A06686256DBA007C5EEA

 A little back-of-the-napkin math from your screenshots leads me to believe that the phase difference is about 3-4 milliseconds. That doesn't seem unreasonably inaccurate.