How do I hook up a encoder to a PCI-6220 daq

[bmfuller]

I have an encoder with 12 pins: Ua0 Ua0_ Ua1 Ua1_ Ua2 Ua2_ Up Up Sensor 0V 0V Sensor UaS Vacant Vacant I am not sure how the encoder signals get tied to the Daq board and how or if I need to connect something to a clock type input. The Linear encoder company (Heidenhain) is also asking what the measuring step i desire (1 microsec or 5) Can someone help?

[stilly32]

Hi Bmfuller,

That looks like a differential encoder. I would take a look at this KB:

http://forums.ni.com/ni/board/message?board.id=70&message.id=5557

Once you get that working, you'll just need to set up a linear encoder task and use the counters. Here is a good starting point for the connections:

http://digital.ni.com/public.nsf/allkb/f6beb62f7562ea5c86256f12004e42c7

I'm not sure what they mean by "measuring step" especially in terms of microsec - did they mention what effect that had on measurements?

Hope this helps,

Andrew S.

National Instruments

[Buechsenschuetz]

This is an incremental encoder, i.e. an encoder which does not only translate motion into a pulse train but into two pulse trains with a phase shift of 90 deg.

Depending on which pulse (a or b) arrives first you can also detect direction of movement.

The pulse outputs are RS422 compatible. If you want to make use of the benefits of RS422 communication (differential transmission, hence less sensitive for environmental electrical noise and reference level shifts between devices) you can connect just one of the lines of each output to a digital TTL compatible input.

The Uaz_/Uaz output is the reference channel giving a pulse when the encoder has reached a certain (fixed) position.

I do not know how to decode an incremental two-phase pulse train in software, I have only done this in hardware so far...or have used boards which have implemented this feature like NI's motion controller boards.

Of course the 4 um/20 um data do NOT refer to time resolution but to displacement resolution. I am not sure what the manufacturer means by the interpolation procedure. Some people decode each edge of each pulse and thus receive 4 times the number of pulses.

[Buechsenschuetz]

PS. If you want to make use of the RS422 advantages, or if you have a rather long cable between the encoder and your acquistion device you should use a RS422 to TTL level converter such as the AM26LS32.