Electronic cam

Hi,

I would like to setup an electronic cam and I'm not sure if it is possible to do with my current setup. I have a Turbo PMAC2 Clipper with two stackable boards (ACC51S and ACC-8ES) with 4 servo motors connected.

From what I've read it sounds like I need to connect my external frequency to an incremental encoder input. Since I'm using the 4 original channels for my motors I was wondering if the handwheel inputs could be used. If so then is there any more information available than what's in the manual.

Thanks!

Yes, the handwheel inputs can be used as masters for an electronic cam. Most people do this through our "external time base" feature (whose main limitation is that it is uni-directional -- the master must be counting up).

If you "external frequency" is a single signal rather than quadrature, it should be wired in the the A input of the handwheel channel, and the decode set for pulse and direction: I6810 or I6820 set to 0 or 4, whichever causes the position to count up.

You will need to add two new entries to the encoder conversion table (ECT). The first one will process the handwheel encoder input just as the feedback encoder inputs are processed. So the new entry is Method 0 with a source address of $78410 for the first handwheel, or $78418 for the second handwheel. The result of this entry is a "position" value for the input.

The second entry is the "time base" entry, which uses the result of the first added entry to compute a frequency.

For example, if the 1st 12 lines of the ECT are used (I8000 - I8011), you would add to use the first handwheel channel:

I8012=$078410 ; 1/T extension of Handwheel 1

I8013=$40350D ; Time base frequency calculation using processed HW1 at $350D

I8014= {time base scale factor}

The frequency value will be in register X:$350F. This can be used as a time base master for a coordinate system by setting Isx93 for the coordinate system to $350F. The speed of execution of motion in the coordinate system will be proportional to the input frequency each servo cycle.