Quadrature encoder interface to PCI-6229

[MogaRaghu]

Using PCI-6229 with LV7.1.

I need to connect an incremental quadrature encoder ( A,B and Z ) signals directly to the card and use the CTR0 to give me the angular position information. Encoder is a 2500ppr type.

As per the specification summary of the PCI-6229 card, this is possible. If so which terminals to use ? ( I have also posted  a similiar query in the other hardware forum )

can someone help me out in this ?

Thanks

Raghunathan

[DavidT]

Hi Raghunathan,

The default PFI lines for a quadrature encoder signal are Ctr0 (A = PFI8 B = PFI10 and Z = PFI9) and Ctr1 (A = PFI13, B = PFI11 and Z = PFI14).

Hope this helps.

[MogaRaghu]

Hi David,

That is the exact information I wanted.

But how did you know ?

I spent so much of time going through the M-Series help and such but never could land on this .

Thanks.

Raghunathan

[DavidT]

I needed this exact info sometime ago and found it one this site - i did a search for 'quadrature m-series' and found a KB article.

[MogaRaghu]

Dear David,

the search terms that you gave helped a lot also. I could get sample code for checkout of an encoder with LV7.1. Good.

I am not sur eif you have actually worked with the encoder + LV combination. Normally any optical encoder  will produce  high frequency jitter if it happens to stop just at the point of transition of either the A or B channel . I do suppose that the DAQmx  VI will handle this and not produce spurious counts - or do I need to configure a filter for the relevant PFI lines ?

Thanks

Raghunathan

[DavidT]

I've only used simulated encoders signals from servo drives, and im not sure if there is a major difference in signal jitter with optical encoders, but i have had no problems receiving counts using daqmx. Im sure someone on this board will be able to give you assistance if you do experience signal problems.

[MogaRaghu]

Oh Great !

I think we should shake hands now...

I am also using the encoder output from a servo drive control amplifier ! So I don't  think  there is anything to worry.

Raghunathan

 

[Ryan_V[DE]]

Raghunathan,

The DAQmx VIs will only read in values when the card has actually registered as a change (a physicall TTL level change). You should not have to worry about spurrious counts in LabVIEW. If you do see bizzare data, however, it is possible to add filtering to the TTL lines to prevent any high frequency noise from incorrectly registering as transitions. This can be done in LabVIEW using a DAQmx Channel property node.

Hope this helps,

[MogaRaghu]

Hello Ryan,

Thanks for the clarifications.

I guess I have figured out the whole setup now, thanks to the information in the links given by David and shall actually be checking out the code in a day or two.

Will revert in case of any further problems, which I hiope will not be there.

Regards

Raghunathan

[_Chris]

With these information I can hook up my encoder, thanks!
I'd like to read the encoder value using DAQmx base and unfortunatly it looks like DAQmx base does not handle quad encoder, see http://forums.ni.com/ni/board/message?board.id=250&message.id=15058&query.id=15798#M15058
Any solutions using RLP ?

Thanks

Chris