Quadrature encoder on PCI 6220 DAQ custom digital filter problem

[Greycat]

I am using both counters on my 6220 DAQ for quadrature encoders.  What I am trying to do is filter some bounce that I am getting on the axes.  I want to be able to custom set the minimum pulse width for each encoder (or both the same should be fine). The problem is that the digital filter using DAQmx channel property for each line seems to work fine (I haven't proven that this actually works) but one has to choose from preset values (the smallest being 2.55ms).  I want to reject anything that is less the 10ms.  This document mentions that you can set up a programmable filter based on an external filter clock.  How do you actually do this?  Is there no way to use one of the internal timebases for this?  If so how?  The "Digital Filtering Conciderations for TIO-Based Devices" entry in the NI-DAQmx help states that you can choose one of four different values for a debouncing filter on a PFI line (different values than the previously linked document) and a custom filter value.

OK here is the short question .... is there a way for me to digitally filter the lines coming into my counters to reject anything less then 10ms through software only?  If so, how?  If using an external timebase is required, how do I do this?

Thanks in advance for any help

Greycat 

[S_Hong]

Hi Greycat,

Although the documentation does mention that you can have one programmable filter setting, this is only true for TIO-Based devices. Unfortunately, the NI-6220 is a M-Series, which means that the only allowable minimum pulse widths settings are 125 ns, 6.425 µs and 2.55 ms. More information on this can be found in your NI-DAQmx help under NI-DAQmx Device Considerations » Digital Filtering » C and M Series.

I believe for your application requirement, we would have to look into some oour Counter/Timer devices.

[Greycat]

Thanks S_HONG

I used the 2.56ms setting and it seems to work fairly well under our circumstances ... if worse comes to worse, we might just have to look into a new DAQ or TIMER/COUNTER Card.  Thanks again

Greycat