Power Clipper is able to Drive 4 Stepper and 4 Servos?

[jbeasley]

I was playing around with a Power Clipper looking to replace my Power Brick CNC Controller with a Clipper and some Stepper Drivers so I could use the Brick for another dev project.

I was looking for a way to run the Siemens VFD on the spindle. I currently do through an analog output for speed and digital i/o for direction which are controlled by a sub program (for G Code).

Anyway I was wonder since I'm not using the Filtered DAC outputs on the clipper if I could just write to them directly to control the VFD speed while I used the PFM for the Stepper Driver which worked fine. I then got curious what would happen if I setup a 5th motor and encoder on the #4 Axis Output using the Encoder input and Axis #4 Filtered PWM DAC output and it seems to work fine?

So does this mean you can actually run 8 motors on a Base model Power clipper 4 Open loop Steppers and 4 Closed loop DAC Servos or is this bad practice? What would be the downside?

Thanks
John.

[steve.milici]

Technically, you could have four open loop PFM motor setups (as detailed in the manual) and four filtered PWM DAC motors on the same Power PMAC Clipper.

There are two downsides to this:
1. There is only one set of “real” motor flags for each channel.
2. The internally generated PFM for “feedback” uses “TimerMode = 3” to get the feedback counts in the channel’s TimerA register. This effectively disables the “real” encoder’s fractional-count function.

For #1 you can redefine the flags to an I/O point (as described in the 5th channel setup).

For #2 there is no “work-around”. You will only get the “integer” quadrature counts in the encoder counter for filtered PWM DAC motors.

[jbeasley]

Thanks for the info Steve.

For my application I think the 4 PFM outputs and using the 4th open loop PWM DAC for the Spindle Speed control will work perfect.