Gecko 320s & Charge Pump

[Mike F]

I posted the message below in my project log http://www.cnczone.com/forums/showthread.php?t=6840 recently but have had no replies yet, so I thought I would post it here for comments.

Just thought I'd mention a small problem I had with CNC4PC boards and how I have solved the problem. Way back in the posts I mentioned I had been sent a bi-directional interface board instead of the opto-isolated, parallel port interface card I had ordered. Because of shipping costs and the associated returns hassle, I was persuaded that the bi-directional card would do the job so I went ahead and constructed the control box. My previous testing and movement of the X and Y axes was done without the charge pump or relay board wired in. Happy that everything was working OK, I wired in the charge pump but no matter what I tried, it would not operate as planned. It was wired as per instructions to switch the interface card on and off as appropriate. The relay would switch but I could still drive the motors despite the interface board not receiving power from the power supply. I had noticed that when I plugged the interface board into the parallel port, without the mains power turned on to the box, the LED on the board lit. This was an indication of the problem. The bi-directional board is not opto-isolated and is receiving power from the PC, enough for it to carry on working without a supply through the charge pump. Problem - how can I now use the charge pump to ensure the motors cannot spin when Mach or Windows crashes out? The solution was fairly simple but I am not sure it is a recognised method. What I did was simply take the 5v common (pin 12 on the Gecko) from the mini power supply through the charge pump and then to the Geckos. The charge pump now works just fine. Every time I fault any of the drives, Mach drops out and the relay switches off. I have also tried turning Mach off whilst running and this also trips the relay as does clicking the on screen e-stop. I have emailed Arturo Duncan of CNC4PC but not had a reply yet.

Mike