Limit switch questions...

[alank2]

Hi,

I noticed that the G540 has 4 inputs on it that it says can be used for limit switches. I'm not planning on using home switches at all, but I like the idea of a limit switch to halt if it goes out of range.

It looks like the design is to pass the limit switch to the parallel and let the PC decide to stop if one of the switches is set. That relies on the PC to make the decision and also that the CNC software on the PC is configured properly to listen and respond to the limit switches.

Wouldn't it be better to trigger an estop on the G540 directly if a limit switch is triggered? No PC involvement, no configuration concerns, etc. You could do it by running a bunch of normally closed limit switches in series with the E-Stop switch or other method. This way if any switch is triggered, E-Stop or any limit, it issues an E-Stop on the G540.

If that were to happen the G540 says it releases all motors. Does that mean you could manually rotate the axis until the switch is no longer closed to get out of E-Stop?

How quickly can the G540 respond to an E-Stop? Is there still motor travel if the motor was moving quickly at the time? I guess where I am going with this is can the limit switches get crushed before the stop can occur?

Thanks,

Alan

[ger21]

I guess where I am going with this is can the limit switches get crushed before the stop can occur?

Imo, limit switches should never be mounted in such a way that they can be crushed by overtravel.

I don't know the answer to your question, though. Although if it releases the motors, then it may move quite a bit, depending on how fast you're going.

[alank2]

Hi Gerry,

Good point; one I didn't think of!

Thanks,

Alan