PXI 6224 linear position encoder resolution question

Hello,
I am using Quadrature Encoder connected to the counter 0 of NI PXI 6224. As shown in the picture, the decoder is working at X4 mode, I set Distance per Pulse as 2. The measured waveform looks like the resolution is 0.5.
My question is:
                         Isn't the measurement resolution equal to Distance per Pulse?
Thanks,
JSI
Attachments:
couter0.jpg ‏50 KB
display.jpg ‏311 KB

It's a case of somewhat ambiguous terminology.  I've never been real happy with their choice of the term "pulse" for configuring quadrature encoders -- I would prefer a term like "cycle."
The value you wire in should be the distance represented by 1 full quadrature cycle.  (Since this will be the distance from rising edge to rising edge on one of the quadrature signals, you can kinda see how someone decided to refer to that span as a "pulse.")   If you measure in X4 mode, you'll produce 4 increments of measurement per cycle.  That's why you see the 0.5 quantization when wiring a value of 2. 
Generally, when I find such ambiguities in meanings of inputs, I run little test cases to help me figure out how things really work.  I've found this to be more reliable than counting on my memory. 
-Kevin P.

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