encoder losing count

[V_Jain]

I have a 1000 line count incremental quadrature encoder on a DC motor and it seem to be losing count when measuring angle with PXI 6259 M- series DAQ, LabVIEW 8.5 on a RealTime target system (running at 5000 Hz loop rate)

I'm using a US digital differntial to single ended converter to connect it to BNC 2120 (PFI 8/9 for channel A and B, 5V for power and ground).

Any advise for troubleshooting? Also where in the code should I incorporate the gear reduction ratio ? 

Searched in the forum but did have much luck. (Please see attached vi for angular measurement). 

Thanks for the help. 

[jschwartz · Accepted solution]

Hi V_Jain,

A good place to start is to use a shipping example located at Help >> Find Examples.  Once this opens, make sure you select the Browse tab in the top left then double click Hardware Input and Output >> DAQmx >> Counter Measurements >> Position >> Measure Angular Position.vi.  These examples are proven examples which are usually a good place to start any program.  This code will give you a good idea whether or not your hardware is working properly.  Also, the gear ratio can be incorporated after the read (change your data by some multiple).

[V_Jain]

Jim,

Thanks for the help. Your suggestion was very useful to isolate the hardware issue.