Chines Spindle and VFD setting of my Estops can any one help (EMI i think)

[Doddy]

the voltage is of my Arduino which is 5v but i have heard that if you run the Mega you can use 12v
again my apologies for not getting back to you when you was kind enough to answer. not me at all

Hmmm, Mega = Arduino Mega?, based on the AT MEGA 2560 MCU, still runs at 5V, but the on board regulator will provide the 5V required by the MCU. The I/O remains, however at 5V. AndyUK touches on ways to improve noise immunity, but with an Arduino-based system (and 5V logic) your best bet is to use opto-coupled inputs with a 12V (plus) input drive system onto the optos. The Arduino as-is is likely to be susceptible to noise.