[CJL5585]

Well, Sorry it is not that simple

In order to wire Limit switches on a machine via the parallel printer port, one has to address a couple of items.

1. It depends upon the type program that you are using to control your machine. Examples: Mach 3, Turbocnc, or one of the many others.

The various programs on the market provide the built in code interfaces allowing communications via the Parallel printer port. On some programs the pin numbers utilized are programmable, on others the pin numbers may be fixed. Anyway, the set-up for Limit switches and home switches are done thru your control program software. If you choose your own pinout in software, just be advised that some pin numbers cannot be used as both inputs and outputs and may not work properly. Also some of these programs allow a software E-stop.

2. A hardware E-stop is the only way that assures that the machine will stop every time. It is wired with the e-stop pushbutton being a normally closed switch. When it is pressed, the circuit is opened, killing power to some or all of the machine electrical power. It does NOT allow the operator to continue on with a completion of the task that was started, in many cases, especially if machining a part, without starting over from the beginning. What part of the equipment motion that is stopped depends upon the design function and wiring of the E-Stop power circuitry.

Hope this helps you understand the process a little better. I will attempt to attach some wiring diagrams for the standarized parallel port pinouts used by most of the control software programs. The diagrams are for a breakout board which is no longer manufactured, but almost all breakout boards use the same pinouts and have identical functions as this one.

Jerry