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CNC controller Mk3/4

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Overview

PlanetCNC hardware:
PlanetCNC series of USB CNC motion controllers serve as a link between a personal computer and motor drivers that support step/direction control. PlanetCNC series of motion controllers are compatible with most motor drivers. Controllers use the USB or Ethernet port, available on all modern computers and laptops. PlanetCNC motion controllers can serve as direct replacement or upgrade for many parallel port breakout boards.

PlanetCNC software:
PlanetCNC motion control system provides a complete, fully integrated software/hardware solution. Additional machine control software is NOT required. The PlanetCNC TNG motion control software is a dedicated application, designed to fully exploit the features of the purpose-built hardware. It has many advanced features to assist day-to-day CNC machine operation.

PLEASE NOTE:
PlanetCNC controllers are compatible only with PlanetCNC motion control software and vice versa.

Features and specifications

PlanetCNC TNG sofware

PlanetCNC motion control system requirements

Minimum system requirements

Mk3/4 - 4 axis USB CNC controller

Hardware installation

Installation of PlanetCNC Mk3/4 controller requires a USB equipped PC or a laptop, along with motor drivers appropriate to the motors in use. The Mk3/4 controller is compatible with the vast majority of motor drivers that use step/direction signals.

Optional support hardware can be employed to customize installation to suit user requirement. Such as opto isolative adapter boards for safer and robust connection with external equipment.

For maximum flexibility in controller layout, a ribbon cable and plug kit is available. This aids the construction of longer cables and ensures plug-in connections correspond to the USB CNC Controller pin outs.

IMPORTANT: Controller should be powered with an external power supply. Mk3/4 - 4 Axis controller hardware requires 8 - 24V DC supply. Power supply should be at least 200mA.

Mk3/4 - 4 axis CNC USB controller description

Mk3/4 AXIS connector

Each connector controls one motor driver. Controller has 4 connectors for axes 1-4.

All signals are also available on screw type connector and 25 pin header.

Axes are usually named like this: Axis 1=X, Axis 2=Y, Axis 3=Z…

On some machines this can be different. For example foam cutter uses names such as Axis 1=A, Axis 2=Y, Axis 3=U, Axis 4=V. Lathes use Axis 1=Z, Axis 2=X. Configuration of axes, as well as their naming can be set in File/Settings/Axes.

CONNECTOR PIN DESCRIPTION:

+5V: +5V power. Motor drivers can take power for logic circuit or common anode connection from the USB controller.

ERR: Error signal from driver to controller

STEP: Provides a STEP signal of minimum 12 us pulse width to the motor driver.

DIR: Provides DIR or DIRECTION signal to the motor driver.

ENABLE: Provides an ENABLE signal for motor drivers. When the ENABLE signal is lost due to output command, E-Stop or limit switch activation, motor drivers will deactivate. A dedicated E-Stop switch connected to the CTRL or INPUT connector can control the signal. It can also be operated by limit switch activation, software command or on shutdown of the control software. This arrangement provides a useful safety feature that can be user-configured to operate under manual and/or computer control.

GND: Ground connections

Mk3/4 JOG connector

Switched operation of JOG 1-8 controls manual jogging. Jogging keyboards can use a ‘SHIFT’ key, allowing Mk3/4 controller users to jog additional axes or toggle the option of jog ‘step’ mode. ‘SHIFT’ key function is defined in settings, as is the ‘step’ value for each key press. Jogging directions and axis assignment can be defined in 'settings'.

CONNECTOR PIN DESCRIPTION:

A typical use might be as below: JOG 1: Jog Axis 1 in negative direction.

JOG 2: Jog Axis 1 in positive direction.

JOG 3: Jog Axis 2 in negative direction.

JOG 4: Jog Axis 2 in positive direction.

JOG 5: Jog Axis 3 in negative direction.

JOG 6: Jog Axis 3 in positive direction.

JOG 7: Jog Axis 4 in negative direction.

JOG 8: Jog Axis 4 in positive direction.

SHIFT: Toggles 'step' jog mode or jogging for additional axes.

ALT1: Selects different jog mode

ALT2: Selects different jog mode

+3.3V: Power for jogging speed POT

POT: Jogging speed POT

GND: Ground connections

Mk3/4 LIMIT connector

LIMIT 1-4 connects limit switches. Switches are connected between LIMIT pin and GND pin.

LIMIT 4: Axis 4 positive and negative limit.

LIMIT 3: Axis 3 positive and negative limit.

LIMIT 2: Axis 2 positive and negative limit.

LIMIT 1: Axis 1 positive and negative limit.

GND: Ground

Mk3/4 controller requires 'Single Input' mode.
SINGLE INPUT: Both axis limit switches are connected to one pin. Direction of travel determines if positive or negative switch is triggered.

If 'normally open' (NO) type switches are used, wiring must be done in parallel method, if 'normally closed' (NC) type switches are used, wiring must be done in serial method. Software 'Invert' options allow use of ‘normally closed’ or ‘normally open’ switch hardware. This feature can be set in File/Settings/Limit/Invert

Mk3/4 CTRL connector

This connector provides inputs for use of MPG pendant devices and E-Stop. Spindle speed encoder for spindle synchronization can also be connected. GND pins provide ‘Ground’ or common connections.

An E-Stop switch attached to this connector can be configured in software to activate/deactivate EStop. E-Stop switch hardware for use with this connector can be NC (Normally Closed) or NO (Normally Open). If NC is used, 'Invert' feature must be enabled in 'settings'. Locking switch is recommended.

CONNECTOR PIN DESCRIPTION:

E-STOP: E-Stop

IDX: Index signal for spindle synchronization

ENC A: Encoder for spindle synchronization

ENC B: Encoder for spindle synchronization

GND: Ground

MK3/4 INPUT connector

This connector provides input for user-assigned functions.

CONNECTOR PIN DESCRIPTION:

IN4: Assignable input 4

IN3: Assignable input 3

IN2: Assignable input 2

IN1: Assignable input 1

GND: Ground

Mk3/4 OUTPUT connector

This connector provides 3 digital outputs for control of external devices. The optional ‘Output board’ links to the Mk3/4 controller using this connector. Output assignment is controlled in software.

CONNECTOR PIN DESCRIPTION:

OUT 6: Digital Output

OUT 2: Digital Output

OUT 1: Digital Output

GND: Ground connections

+5V: +5V supply

OUT 1, 2 and 6 can generate PWM signal, RC servo signal or frequency modulation.

Mk3/4 26 pin header

Pin 1: ENA

Pin 2: STEP 1

Pin 3: DIR 1

Pin 4: STEP 2

Pin 5: DIR 2

Pin 6: STEP 3

Pin 7: DIR 3

Pin 8: STEP 4

Pin 9: DIR 4

Pin 10: E-STOP

Pin 11: LIMIT 1

Pin 12: LIMIT 2

Pin 13: LIMIT 3

Pin 14: OUT 6

Pin 15: IN 1

Pin 16: OUT 1

Pin 17: OUT 2

Pin 18: NC

Pins 19-25: GND

Pin 26: NC/+5V

EXT connector

This connector allows use of EX, I2C and UART protocol devices.

CLK: EXT CLK signal

MISO: EXT MISO signal

SCL: I2C SCL signal

TX: UART TX signal

+5V: +5.0V supply

SSEL: EXT SSEL signal

MOSI: EXT MOSI signal

SDA: I2C SDA signal

RX: UART RX signal

GND: Ground

CAN connector

This connector allows use of CAN protocol devices.
PLEASE NOTE: CAN INTERFACE IS CURRENTLY UNDER DEVELOPMENT

GND: Ground

CANL: CANL CAN signal

+5V: +5.0V supply

+5V: +5.0V supply

CANH: CANH CAN signal

GND: Ground

Mk3/4 USB connector

The Mk3/4 USB CNC controller connects to computer via the USB port. The port uses the USB 2.x standard.

Mk3/4 Power terminal

The controller should be powered with an external power supply.
Mk3/4 - 4 Axis controller hardware requires 8 - 24V DC supply
Power supply should be at least 200mA

Mk3/4 LED indicators

The user is provided with helpful feedback and live ‘status’ information via on-board LED indicators.

There are four indicators:

POWER: Lights when the controller is powered.

DATA: Indicates controller functions.

LINK: Indicates controller communication.

STATUS: Blinks to indicate controller function is ‘good’.

Connection diagrams

Wiring of limit switches

Mk3/4 controller has 4 designated limit switch inputs. This means that 'Single Input' method of wiring must be used. When 'Single input' method is used, both limit switches are connected to one limit pin.

Mk3/4 uses screw type connectors which makes the connection even simpler.

Parallel wiring of NO type switches:


Serial wiring of NC type limit switches:


Wiring inputs of Mk3/4 controller

Mk3/4 has 4 assignable inputs. Bellow is wiring diagram of switch/button, connected to Mk3/4's assignable input. Inputs function is assigned in settings.

Connection motor driver to Mk3/4 controller

Wiring diagrams for COMMON CATHODE and COMMON ANODE connection of motor driver:

In-depth connection guide for different types of motor drivers can be found here: How to connect motor drivers

Picture bellow demonstrates the connection of 2.5A Motor driver to Mk3/4 controller and connection of stepper motor and power supply to 2.5A motor driver. Since this motor driver uses 10-pin header and ribbon cable, connection is pretty much trivial:

Picture bellow demonstrates connection of motor driver to Mk3/4 controller and connection of controllers external power supply: