[serviceman]

you normally get 4 m codes in the fully stacked io board most tm-1's and mini mills do not come with 4 they come with 2 m codes. the jack on the side of the machine you really do not need unless you are running an m-code operated servo control. the only reason for that is the m fin signal which you can still get from the io board without the connector. if you only want to fire an m code you tap into the realys on the top left of the io board they are labelled. if you need more than the m-codes supplied with the machine you can get the 8m option which will give you 4 more m codes for a total of 8. i probably would not run more than like 5 amps at 120vac if you need to switch something that draws more you should use a contactor and fire the coil with the m code.