Wiring diagram for limit switches with g540?

[Goemon]

Please can someone direct me to an accurate wiring diagram for limit switches with a G540 on a 3 axis CNC machine?

There are multiple diagrams if I google it but they are all different which means I can't trust any of them.

The diagram on the Gecko site is not helpful because it only shows wiring for a 2 axis machine (with 4 instead of 6 switches).

If there is a diagram that someone here can confirm is accurate, I would really appreciate a link....

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[john-100]

the diagram on page 8 of the G540 manual just shows home switches for 4 axis

G540 REV8 Manual.pdf

assuming your using mechanical micro switches not electronic proximity switches

you can add another normally closed switch to the switches shown in the G540 manual



note - the switches labeled home switches act as both home & limit switches

when homing mach 3 will not trigger an e-stop even though the same input is used
for both home and limit functions

John

PS

Homann designs wiring diagram on 2 PDF pages

[Goemon]

the diagram on page 8 of the G540 manual just shows home switches for 4 axis

G540 REV8 Manual.pdf

assuming your using mechanical micro switches not electronic proximity switches

you can add another normally closed switch to the switches shown in the G540 manual



note - the switches labeled home switches act as both home & limit switches

when homing mach 3 will not trigger an e-stop even though the same input is used
for both home and limit functions

John

PS

Homann designs wiring diagram on 2 PDF pages

Thank you. That is exactly what I needed.

I am using Linux CNC. I am assuming that the wiring would be the same as it is for Mach3?

[john-100]

I have not used Linux CNC but I think it uses the printer port the same way



John

[Goemon]

I have not used Linux CNC but I think it uses the printer port the same way



John

It does. I just get a little anxiety about buying peripherals that specifically say they are for use with Mach3, I am assuming that touch plates and limit switches are universal and compatible with many (or most) software platforms but I guess there is one way to find out for sure...

So far, I am feeling good about my decision to use Linux CNC. It wasn't difficult to install and the interface is not as different to windows as some people said. I am just hoping I can use it with all the accessories I want....

It's a little annoying that sellers only supply scripts for Mach 3.

[john-100]

the original IBM parallel printer port connections for Mach 3



from what I understand both Mach3 & Linux CNC use the first printer port like this -

the status port to monitor 5 inputs including E-stop at hexadecimal address 379h


the Data & Control latches provide 12 outputs

the Data latch at 378h provides 8 outputs that normally sent 8 bit data to the printer (pins 2 to 9)

the Control latch at 37A h provides another 4 bit output

if you slave 2 motors it makes sense to ensure they are driven by the same latch !


in Mach 3 and presumably Linux CNC

additional printer ports can be configured to use the DATA latch as either 8 outputs or 8 inputs

the Mach 3 PDF manual can be downloaded here :-

http://www.machsupport.com/wp-conten...all_Config.pdf

partial G540 circuit diagram


from the diagram you can see the limit switch inputs need to be able to ground the input

ideally N/C switches in series as a broken wire will stop the machine
or
N/O switches in parallel -
the danger a broken wire is not detected until its too late !!

electro-mechanical micro switches are easy


it not as easy to use proximity switches :-

proximity switches with N/C PNP open collector outputs can be wired in series
the output from the last proximity switch is the positive supply to the proximity switches and will require an additional interface circuit to work with the G540
( or other BOB's that work with an input switch to ground)

proximity switches with N/O NPN open collector outputs
will easily interface with the G540 as they can be wired in parallel
and will be connected between the G540 supply negative and the input terminal

the problem is you would not detect a broken wire


John