Encoder Reading Issues

[Maciekdp]

Hello,

I'm trying to read a differential quadrature encoder signal (linear) with my 6259 M series card.  The encoder signal comes from the Xenus servoamplifier.  I'm using a converter from US digital to convert the signal from differential to single - ended (i.e. from A, A', B, B' to just A and B).  My code is based on an example I found.  Also, my terminal box is a BNC-2120.  The code seems to work fine at first, but sometimes when I move the shaft to another location, the code shows constant movement, even though the shaft isn't moving.  I enabled duplicate count prevention, but it doesn't seem to have an effect.  Any ideas?  Should I implement an analog filter?  How do you choose cutoff freq?

Thanks

maciek

[Maciekdp]

Ok, so after doing some research it seems that I need to use a debouncing filter.  Now the default settings are 125ns, 6.425us and 2.56ms.  I need something between the last two.  How do you select a value different than these?

m

[Chris_W.]

You can set the minimum pulse width of your counter input using a DAQmx Channel property node. It is in the property path of Counter Input:<Measurement type>: Digital Filter: Enable/Min Pulse Width. Though I think if you put something that is not one of those three values, it will coerce it to use the nearest value for min pulse width.

Chris W

Message Edited by Chris W. on 02-16-2009 11:13 AM