During testing I found a new EMC issue. This time its the motion controller. When increasing the arc power, the dynomotion card suddenly becomes unreachable and the CAM software chrashes. I was afraid this would happen, since I’ve seen it in other CNC milling machines that use the Dynomotion card, so I took many precautions. However, the issue still popped up. My card is mounted in a shielded enclosure and has galvanic isolation on all used interfaces (including the USB interface). Even now the issue still persists. This is a mayor problem now which will consume quite some debugging time.
I know its EMC since the card works perfectly when the arc is turned off. The current counter measures are:
- 4 stage common mode filter on mains power
- Shielded enclosure
- USB optical isolator
- Interfaces to stepper drivers are all optically isolated
- USB ferrite bead located next to the controller
- Low noise linear power supply
Suggestions anyone for additional measures?……..
The picture below shows the current state of the motion control cabinet (click the image for large picture).