- As PlanetCNC, the solution is more expensive than hobbyist solutions, but there's a reason for it.
## Microcontrollers: USB, Arduino, Rasperry Pi, TinyG, & More :
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CNC Microcontrollers are a relatively new development made possible by continued advances in miniaturization and software. The idea is to put everything you need on one small circuit board, or perhaps a microcontroller board with a daughterboard commonly called a “Shield”. a quick list of all the most popular CNC Microcontrollers:
### GRBL+USG:
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@@ -108,3 +108,70 @@ The TinyG codebase was forked from grbl in 2010 and has been going its own way e
- grbl is an XYZ 3 axis controller (i.e. a cartesian robot). TinyG is a 6 axis controller that runs XYZ and also ABC rotational axes.
- In grbl the velocity profile during acceleration and deceleration looks like a pure trapezoid in time. For example the move starts at zero velocity, then velocity ramps in a straight line to the target velocity, then decelerates in a straight line back to zero. In TinyG the velocity profile is an S curve that ramps to the target velocity during acceleration and in reverse during the deceleration phase. The means that you can run to motors harder in transition and hence operate at faster accelerations and decelerations. It also means there are fewer machine resonances excited (that cause chatter and other problems) as the jerk term is controlled. Jerk is a measure of the impact a machine is hit with during a velocity change. See: TinyG driving an Ultimaker and driving a Shapeoko. The machines are not fastened to the table and don't jump around because of the jerk control.
## Controller Electronics:
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The electronics that control a CNC are basically composed like this:
1. Each axis is controlled by one or two motors ;
2. Each motor gets its instructions from a driver ;
3. A central breakout board sends instructions to the different drivers, based on the information it gets from a control software;
4. A control software, which is directly connected to the controller with a transfer protocol (usually USB or Parallel DB25). Except on industrial CNC machines, the control software is usually running on an external device like a computer.
### CNC Breakout Boards :
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Thee CNC Breakout Board has two functions i.e. Translate the signals used to run a CNC machine to and from the signals a PC expects and Isolate the PC Motherboard from electrical problems that would otherwise fry the Motherboard.
There are two types of Breakout boards:
1.**Parallel Breakout board**
2.**Motion Control Boards**:
### Parallel Breakout board:
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Parallel CNC Breakout Boards connect to your PC’s parallel port and convert those signals to screw terminals which you may then use in point-to-point wiring to connect up the rest of your system. These are the most commonly used type of breakout board. They’re simple, and relatively inexpensive
***Drawbacks***:
There are limitations on its performance, particularly when used with Windows software, such as with Mach 3. You will be limited in how quickly you can send and receive the signals from the board, which may in turn limit the performance of your CNC.
The second limitation is that of compatibility. PC manufacturers are gradually phasing out parallel ports altogether in favor of USB, and in the meantime, they are sharply controlling the power consumption of these interfaces. As a result, many later model PC’s use 3.3 volt signals instead of 5 volts.
Lastly, parallel ports have relatively few I/O channels. Boards typically support 11 or fewer outputs and only 5 inputs. As one can imagine, these go quickly, especially if they are trying to connect an elaborate control panel to their machine. For this reason, either have a choice to “keep it simple”, or will need to add one or more additional boards to get the job done.
For most low end applications, this is not a problem. For better performance, we need to use a Motion Controller .
### Motion Control Boards:
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The Motion Control board is a piece of dedicated hardware whose sole purpose is converting motions to driver control signals. It can’t really be interrupted because it doesn’t do anything else, which is great in terms of providing smoother and higher speed motion. the role of a Motion Controller is to accept higher level commands and generate the pulses. The result is much higher performance at a slightly higher cost.
***Choosing guide for CNC Motion Contoller Board***:
- It is vital for the machine’s stable functioning to get a controller with enough input and output signals. It will help maintain the flow, but it will also increase the durability of the machine
- To control the axis number used simultaneously, calculate and compute, you need a controller with enough processing power.
- A controller with about 1000 block looks ahead functions will be great to calculate with higher speeds and accuracy.
- The controller will be able to supply power to the IO port if it’s the best one. A higher voltage supply is what makes a difference. With a high voltage supply, the controller will let you work efficiently and without any disruptions.
- Another important consideration is making sure that the motion controller has enough outputs to control your various peripherals. The most basic PnP will have 1 output; usually a nozzle vacuum solenoid. More complex machines may have additional solenoids for exhaust and blow off, switches for pumps and lights, solenoids for feeders, etc.
- Recommended control separate peripheral and USB power supply connections is more than a blessing
## Recommended Models :
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Based on lots and lots of different builds, many people recommend a [Smoothie](http://smoothieware.org/) based board for most machines. Smoothie is an Open Source motion controller firmware that runs on a variety of affordable, all in one boards. It's easy to configure, well documented and works great with OpenPnP.
Some Smoothie based boards that are known to work with OpenPnP, and which you can buy online are:
-[Smoothieboard](http://smoothieware.org/getting-smoothieboard): The original. Buying this board helps support the creators of Smoothie. Available with up to 5 stepper drivers and 6 MOSFET outputs.
-[Cohesion3D Remix](http://cohesion3d.com/cohesion3d-remix/) : Created by an OpenPnP forum member, this board is designed with PnP in mind and has up to 6 stepper drivers and 6 MOSFET outputs. This board is great for larger, more complex machines.
-[Azteeg](http://www.panucatt.com/default.asp) Panucatt Devices sells a series of Smoothie based boards called Azteeg. There is a review here.
-[Re-Arm](http://www.panucatt.com/default.asp) : Panucatt Devices also sells the Re-Arm, which is a Smoothie based board in the form factor of an Arduino Mega. This allows it to be used with existing RAMPS 1.4 boards which are common in the 3D printer world.
Note that MKS Smoothie clones are not recommended. See this [FAQ](http://smoothieware.org/troubleshooting#what-is-wrong-with-mks) for more information on why.
- the Ethernet SmoothStepper (ESS) is a high-performance, **6 axis external motion controller for Mach3 and Mach4**. it is capable of producing pulses at very high frequencies and with extremely low jitter compared to the Parallel Port driver and microcontroller based solutions
- Motor control capability Up to **6 Motors (Step and Direction, Quadrature, or CW/CCW)** and max frequency upto 4 Mhz.
- The Ethernet SmoothStepper (ESS) requires an external 5 V **power supply** to operate. The ESS has a typical current draw of 0.3 A (when Ethernet communications are active) but can consume up to 0.5 A. [We strongly recommend at least a 1.0 A supply.](https://warp9td.com/index.php/documentation/doc-ess#EssExternalPower)
The ESS is intended to connect to your equipment via a “parallel port breakout board”, This is a board that has one or more connectors that have a parallel port interface. For a Spindle that is controlled by a 0V to 10V Analog signal, you will need a Break Out Board that can convert a PWM, Step/Dir, CW/CCW or Quadrature signals into a 0V to 10V analog signal (and also provide one or two relays to control the VFD.
***Recommended paralled BOB for ESS***:
One of the best breakout boards for using with the ethernet SmoothStepper is the [C25XP - Smooth Stepper Integrated Board](https://www.cnc4pc.com/c25xp-smooth-stepper-integrated-board.html) from CNC4PC, a Florida-based manufacturer. C25XP breakout board can be bought either as a separate breakout board or with ESS integrated to it.
