View Full Version : Whats the difference?????

03-17-2009, 09:10 PM
Got an early 80's Bridgeport Boss and would like to PC it someday. For the moment I am just trying to get a grip of every thing I will need to do the job right.
1st question What is the different between an interface,breakout board and buffer board.
2nd qestion What is the different between Motion board,breakout board and drivers.
Thanks Dave

03-21-2009, 12:10 PM
1. Interface: anything that connects to circuits or systems.
2. Breakout Board: any card that takes multiple signals in a system or cable and allows pin level access. it "breaks out" individual signals from a group or signals. (i.e parallel port 25 pin to individual terminals for each signal). Breakout's typically handle input back to the control and isolation is better on inputs to break ground loops and noise paths. Breakouts also can have added outputs for powering relays for external control (Spindle, Flood, Mist, etc)
3. Buffered: Amplified (to provide more drive current or drive voltage or both). It provides better noise immunity on low level signals and allows level shifting (moving 3.3V signals to 5V logic level). Most parallel ports do not have enough drive to source older opto input motor drives so the signals need to be "buffered". Buffering lowers the impedance and the levels so driving a signal down a cable goes not result in as much loss and noise.

4. Motion Board: A card that takes trajectory information and turns it into cooridinated signals to drive downstream motor drivers. You can also do the same thing with a PC and parallel port software (like MACH3). Most motion cards have to have specific control software and ti may or may not be setup to do CNC work (take g-code and put out motor drive signals.

5. Driver: anything that "drives" something. In the CNC context it typically means the hardware that makes the motors turn. It takes the step & dir signals from a "controller" (see motion board/software above) + breakout and provides the power to run a specific type of motor (stepper or servo). Best example of a "driver" is the Gecko Drives.

You can CNC your Bridgy with:

PC with one parallel port (or add-in PCI port card)
MACH3 Software Controller
Powered Buffered Breakout Card
Motor driver for each motor.
DC Power Supply (to match motor and motor driver current & voltage)

That's an oversimplification but it's the core requirements.

TOM Caudle
Totally Modular CNC Electronics