routercnc_MK3

[EddyCurrent]

This is a similar 5v version, SainSmart 4-Channel 5V Relay Module for PIC ARM AVR DSP Arduino MSP430 TTL Logic Specializing in Arduino compatible development boards and modules, oscilloscopes and other electronics.

Circuit drawing

As Irving said regarding active low etc., as Dean said regarding probe and 24v circuit.

I'm a big fan of 'volt free' contacts, i.e. in this case the contacts of the relays, it lets you interface different voltages from different sources without problem and if you want to add other things into the circuit later on you won't have to modify existing parts to accommodate it. As Irving says, fewer components is more reliable but in this instance my preference is to use a relay.
In my case I eventually used 3 wire proximity switches for the home switches directly into the bob and a PILZ relay with the limits in series with E/Stop switches and then one of the PILZ relay contacts into the bob.