I've been getting a lot of interest in yet to be developed parallel port breakout add-on board for the Arcsin. However, I've just been too busy to put it together yet, so meanwhile, I put together this temporary way to connect your Home/Limit/Estop switches up to the Arcsin. Just remember, you can cook your motherboard if you don't know what you are doing here, so I strongly suggest that you spend the $10 on the parallel port PCI card if you are going to experiment. Buildyouridea.com is not responsible if you let the smoke out of something! Here is what you'll need:
These are the pinouts that I use. There are many different ways to configure your CNC machine to use these inputs and outputs, but I've only included the configuration that I use on my cnc machines.
To make the connection, you'll need a 40 pin hard drive cable that you don't mind cutting up. Hack one of the ends off the cable and strip back the insulation on the signals that you want to use. You can also prep the wires by tinning the wire with solder to get it ready for attaching the pullup resistors. You might need to use an ohmmeter to figure out which pins go to which wires.
The picture below shows the parallel port pinout for the Arcsin's 40 pin header.
This image shows how the parallel port pins are configured.
Here is a basic schematic that shows how you can configure the parallel port inputs. Just connect the Home/Limit/Estop to each of the switches shown below and then configure your CNC software to use these pins. The 330 Ohm resistors are optional and are primarily used to protect your parallel port in case you short something out.
To control your spindle motor, just connect this circuit to the output pin of your choice (I use pin 14). Don't forget to pick a relay that can handle the current of your spindle motor!