Newbie question: wiring encoders into a 6602 board

[del-donno.1]

Hello, 
    I've been browsing this website and forum extensively recently in research for an upcoming project in which I'll be using three encoders to measure transmission error in a gearbox.  We have a unused PXI-6602 card in our DAQ system for this purpose.  I've worked a lot with accelerometers being read by our 4472 cards and am familiar with how that works, but the world of encoders and digitial counters is new to me.  What I'm stuck on at the moment is the physical connection between the encoders and the 6602 card.  There seems to be a great deal of discrepancy between different pin arrangements out there.  The 6602 (according to the manual) seems to only require three inputs (A,B,Z) whereas most encoders have anywhere from 10-20 pins.  Furthermore there seem to be several cabling standards, such as SSI, binary and so on.  IS there any specific type that will/will not work with my 6602 card? 

Thanks in advance for any pointers, I'm just trying to sort this all out in my head before we start looking to actual hardware.

[Kevin_Price]

- I've got to wonder if those 20-pin encoders are absolute encoders?  The 6602 encoder interface is intended to work with incremental encoders.

- The best kind of encoder signal output to the 6602 would be TTL quadrature, and I'd further suggest the option of a quarter-cycle-gated index pulse as well.  If your environment is electrically noisy, you may need an encoder with differential output and then provide circuitry near your PC to convert to TTL for the 6602.

- From what I can see, SSI appears to be something like a standard communications protocol for absolute encoders.  I've never dealt with it, but that's probably not what you need here.

- Your measurement will likely need hardware-level synchronization of the encoder position readings.  A 6602 can do this for 3 incremental encoders.  I won't go into details since you're new to counters, but just wanted to let you know that you can get there from here.

-Kevin P.

[del-donno.1]

Thanks Kevin, you are right, I had been looking at absolute encoders, when incremental is what I should have been examining, and now I see the familair A,B,Z (plus power and ground) that I had been expecting.