DB25 Male to DB25 Female Pass Through Breakout Board (BOB)
Typical Parallel Port Input (for switches, probes, etc.)
Typical Parallel Port Outputs (for controlling relay drivers, etc.)
The Xylotex Drive Box and the BOB do not use, control or power the signals above.
These are all under control of the software used (Mach3/4, LinuxCNC, MachineKit) and powered by the parallel port being used (i.e. from PC parallel port or from external signal generator). Check the software for setup and use of these inputs and outputs.
In the example shown above an NC switch is connected from GND to DB11 (Pin 11).
Pin 10 - STOP Switch
Pin 11 - X Limit/Home Switch
Pin 12 - Y Limit/Home Switch
Pin 13 - Z Limit/Home Switch
Pin 15 - Touch Probe
Pin 1 - Enable (PWM/Charge Pump)
Pin 14 - Spindle/Laser/Torch Enable
Pin 16 - Spindle Direction
Pin 17 - Coolant Relay
The board can be used with STOP switches and Limit Switches:
Rather than plugging this directly in to one of the drive boxes, an easy to use configuration would be:
PC -> 3 ft. parallel port cable -> BOB -> 3 ft. parallel port cable -> Drive Box.
Extra 3 ft. parallel port cables are available in the Accessories category.
This BOB (DB25_BOB_ST) comes with the 5V 2-pos Screw Terminal Shown in the photo. It does not come with the 5V Barrel Jack shown just below the 2-pos Screw Terminal. Use this version if you have a 5V power source with pig-tail connections/ends
This BOB passes All signals directly from one DB25 connector to the other.
The Standard CNC Parallel Port I/O are routed to screw terminals shown on the left.
This includes Pins 1, 10, 11, 12, 13, 14, 15, 16, 17.
These I/O connected to resistors and can be pulled up using the +5V terminal.
The typical inputs on Pins 10, 11, 12, 13, & 15 also have bypass capacitors to GND to help reduce switch bounce.
A +5V & GND power source should be attached to the board to pullup the input signals to a known state. You can use a standard 5V wallwart. Or cut of the un-needed end of a USB port. Use the red wire for +5V and the black wire for GND. This will help prevent -floating- signals
The inputs are typically wired to normally closed (NC) switches which will have the other side wired to GND.
For example an NC limit switch could have one connection to DB11 input and the other side to GND. When the switch is hit (opened) the input will go high signaling the control about the activity.
Software must be setup in the control (PC or BBB) to make proper use of the inputs and outputs. Software should also be setup to mask switch bounce that may occur at the inputs.
The outputs are not buffered and will have the voltage provided by the signal source (PC or BBB).