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Light curtain implementation - best practices for CNC router

CNC router with a CSMIO IP-A controller and CSMIO-MPG module and handwheel. The software is SimCNC. The machine is today equipped with an e-stop button in series with the one in the handwheel running to a Pilz safety relay that controls the HV-relay of the machine.

I would like to equip the machine with a safety light curtain to prevent accidents of the operator entering the machine envelope while the machine is running. This could be done quite easily by adding the light curtain to the current e-stop relay, however, the operator sometimes needs to jog the machine while inside the machine envelope and I'm not sure what would be a safe way to allow this.

My current thought is to use the enable button of the handwheel and suppress the light curtain signal as long as this button is pressed.  Furthermore, I plan to use the zero-speed signal from the servo drives and spindle VFD to detect axis movement or spindle rotation. So if the light curtain is triggered and movement is detected while the enable button is not pressed an e-stop should occur. 

So the inputs will be light curtain status + zero speed signal from servos + spindle VFD signal + enable signal from handwheel. I assume that all of these signals need to be hard-wired to a safety PLC or safety module? 

Does this sound like a bad idea, or do you guys have any input on an easier or safer way to achieve this?

What you want to do could be done with macros, but it wouldn't be safe.
Therefore, the best solution is to use a programmable safety relay for this purpose.
Thanks to it, you will achieve the functionality you want without compromising the convenience of using the simCNC software.

Thank you for the solution. Can you recommend a safety PLC that is suitable and affordable for this purpose?

This is a great idea but it is important to ensure the safety of your machine and employees. It would be best to reach out to a reputable CNC Machine service provider like Want.net to ensure that everything is set up properly and safely. Want.net CNC provides high-quality machinery services, including installation, repair, and maintenance. Their experienced technicians can help ensure that the safety mechanisms are correctly set up and maintained. Click here to investigate about this site.

Quote from blims on 16 May 2023, 16:08

Thank you for the solution. Can you recommend a safety PLC that is suitable and affordable for this purpose?

Unfortunately, I cannot recommend a specific model of a safety relay.
The safety relay is selected individually for your needs, so you must contact a company specializing in this.





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