This is a much-delayed response. Dunno if the OP still needs help with this stuff so I'll keep it brief for now.
1. I looked up the error codes you mentioned. -200216 doesn't appear that it should apply to the code you posted, unless *possibly* it's a side effect of explicitly setting up DMA or Interrupt transfer *before* configuring the task to have a sample clock and buffer. I'm not real hopeful, but you can *try* making the call to DAQmx Timing *before* setting up your DMA or Interrupt transfer method.
2. The 6602 only has 3 total DMA channels available for counter tasks so unfortunately, you *will* be stuck manually configuring at least one of your encoder tasks for Interrupts. The other 3 should try to use DMA by default and shouldn't need to be configured manually.
If you can change hardware, a newer 6612 counter device or most any X-series 63xx device would support DMA for all 4 counter tasks. This would be much preferred if possible.
3. When you configure Arm Start triggers, you generally need to specify 3 properties, not just 1.
Trigger Type = Digital Edge
Source = terminal of triggering signal (this is the one you *did* specify)
Edge = either rising or falling as needed.
Note: once upon a long time ago (probably ~10ish years?), I found that it seemed to matter that Trigger Type needed to be above the Source and Edge designations. I adopted the habit back then and haven't re-checked whether it's still necessary in more recent DAQmx versions.
There are some other things, but that's enough for now. Meanwhile, I strongly urge you to put effort into neatening your diagram -- both for our sake and your own. A very useful convention is to keep all the DAQmx task/error wires for a particular task in a straight horizontal line.
-Kevin P
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