[helfires688]

Hello all,

I am currently working on a CNC conversion for my Grizzly G0704, and I am hoping to use a motion controller to optimize the stepper drive control interface on a non-slave computer. It is my understanding that these boards (like the SmoothStepper), work to mitigate the issues presented by the fact that Windows is a non-real time operating system. My goal is to create a modular system that will evolve from complete software control to a tactile user console, and it seems like the PoKeys system would be perfect for that. My only question is if the PoKeys core system is a motion control board like the smooth stepper, allowing me use one interface for stepper motions and I/O interface, or if i would be better served dedicating a smooth stepper for my axis drive systems and use PoKeys only for peripherals like MPGs and a milling console.



Thanks for the help!

[BTP]

It's been awhile since I've looked at the Pokeys, and it's always evolving, but the last time I looked at it I think you could drive up to 3 axis from one of the Pokeys. I use it for most of my control buttons and it works well. I would probably go with the smooth stepper for motion control though. Preferably the Ethernet version.

[SCzEngrgGroup]

PoKeys is NOT a motion controller of any kind. It is simply a programmable keyboard emulator.

Regards,
Ray L.

[hoss2006]

As stated the pokeys can run up to 3 axis
"PoKeys Pulse engine (available on PoKeys56U and PoKeys56E devices) enables the control of up to three stepper motors. PoKeys Pulse engine can work in standalone (rapid positioning and speed control mode, homing, jogging via kbd48CNC keyboard) or in slave mode (under the command of the PC application).....25 kHz maximum pulse frequency supported."
I'd also go with the more robust ESS for the steppers, the pokeys is still great for many other input/output functions, home/limits, mpg, etc, it is not restricted to keyboard emulation only.
Hoss

[helfires688]

Thanks every one for the responses, it sounds like I should use SmoothStepper for motion control and PoKeys for peripheral I/O's

[helfires688]

It's been awhile since I've looked at the Pokeys, and it's always evolving, but the last time I looked at it I think you could drive up to 3 axis from one of the Pokeys. I use it for most of my control buttons and it works well. I would probably go with the smooth stepper for motion control though. Preferably the Ethernet version.

Why is the Ethernet version better?

[embraced]

The Ethernet interface is galvanically isolated from the host computer. USB is not - this means that without VERY careful design of the control electronics you will get harmful ground loops that will disrupt the SS.

[SCzEngrgGroup]

The Ethernet interface is galvanically isolated from the host computer. USB is not - this means that without VERY careful design of the control electronics you will get harmful ground loops that will disrupt the SS.

That is not true in the most typical case where the ESS is powered by the PCs power supply. Besides, there's not a reason in the world a USB SmoothStepper can't be isolated just as well by using opto-coupled BOBs and separate power supply.

That said, NONE of my machines have any kind of isolation between the PC and the machine electronics, and none of them have ever exhibited any problems that could remotely be pinned on grounds loops or other interference, when running with the PP, USB SS, ESS, or KFlop. Ground loops and other noise problems are FAR more commonly caused by poor grounding and shielding practices. Simply isolating the motion controller will do nothing to help a poorly wired machine. My machines have the (unshielded) servo motor wires running side-by-side with their (properly shielded) encoder cables, and they've never skipped a beat. On my DC servo machine, the two cables are actually Ty-Wrap'd together for their entire 15+ foot length. On the AC servo machines, they run side-by side for most of their length. The encoder cables are properly shielded. Same goes for the touch-probe wires,one of which runs through the same conduit as the wires for the 12V/85A DC motor that drives my power drawbar. Everything in each system (PC, motion controller, BOBs, VFD, servo drives, stepper drives, relays, solenoid valves, etc.) shares a common ground, and all components are mounted within inches of each other within their enclosures..

Regards,
Ray L.

[embraced]

Ray,

I agree with you. You can easily isolate a USB SS through various methods - but they will add to the cost when this can be avoided by getting the ESS.

I personally have two machines, one using an ESS and one using a KFlop. I've not had any electrical problems with the ESS (dozens of unexplained phenomena in Mach however..). With the KFlop, introducing a noisy AC Servo in direct proximity to the KFlop caused some problems, even with the entire enclosure being designed with the utmost care in wiring practice. An isolator (Olimex type) solved this.

My point is that the extra few dollars spent on an ESS can negate a lot of problems caused by poor practice.