LabVIEW Encoder not reliably returning Rate

[jhersh]

I've sat down and tried using all of the quadrature decoding resources and discovered something a bit odd. In 4x decoding, the 2 odd numbered decoders return rate correctly, the other 2 do not. In 1x or 2x decoding, the first 3 even numbered decoders and the last (odd) decoder return rate correctly.

I've modified the Open and Close VIs for the Counter and Encoder APIs to have them only use the ones that work. If you need the rate output, you can replace these after installing the update. Extract this to C:\Program Files\National Instruments\LabVIEW 8.6 or wherever you installed LabVIEW. If you install a new update or reinstall anything, you need to replace them again. Note that this may cause confusion for your team if you use more than one computer for development and you forget to install these on all development machines.

The downside to this work-around is that you now can only use 2 encoders in 4x mode and 4 encoders in 2x or 1x mode.

You always have the option to write your own rate algorithm based on the distance instead, but that may be less accurate.

-Joe