How many parallel ports are necessary to control a three axis machine?
We suggest three, although it can be done with two. We recommend that you use one parallel port to connect to user controls options: feed hold, feed rate override, joystick and cycle start. The remaining two parallel ports will support up to four axes as well as numerous outputs and inputs that can be used for spindle control, solenoids, switch sensors etc. (This still leaves room to expand with an additional port, which would add capability to control two more motor axes, and more auxiliary inputs and outputs).
