Another Home - Limit switch question

[EddyCurrent]

Simon,

1.I am not sure if I have got the wiring right for the LJ12A's?

They look correct up to a point

2.Is it ok to collect together the LJ12A's for the Y and X axis from both an electronics point of view and a MACH3 angle?

Take a look at this website for details of switches in parallel.
Sensors - Inductive Proximity Sensors
As these act as N/O then when any one of them is activated it will change the state of the bob input, as far as Mach3 is concerned this is fine because you can wire all the home switches to one input and it just cycles round them one at a time. However if you have a slave motor, as you do, this has to be on its own input. So X,Y,Z home switches are into one input, Y slave is into it's own input. Of course you can have them all on an input each but this is wasteful of inputs.


3.Will the LJ12A appear to the BOB like a microswitch and if so will it be N/C or N/O?

N/O

4.I would like to open a relay with the emergency button circuit so that i can turn power off to a few items. Can someone suggest something suitable.

You need to use a NVR (no volt relay). This means the circuit will not reset until you press the 'reset' button.
In the diagram below you could also incorporate the limit switches as shown if you wanted to save an input, I would want the machine to trip if it hit a limit switch.



5.Do the LJ12A's work effectively both in axially approach as passing by?

They need to be in passing by mode because your limits will be physically past or outside the home switches.

link to bob manual http://cnc4you.co.uk/resources/Breakout board HG07.PDF

As cropwell says you could have button that temporarily shorts out the limits if you hit them to let you back off but you could also do this, although I've not tried it myself.
http://www.machsupport.com/forum/ind...1;topic=6722.6