Crimping Connectors for Reliable Wiring

For a visual demonstration of proper crimping techniques, we recommend this excellent guide: Teaching Tech on YouTube

1. Power supply and spade connectors
2. High current connectors
3. Medium and Low current connectors
4. Duet 3 expansion boards

Duet 3 mainboards feature a barrier strip with screw terminals for power supply connections and are supplied with insulated spade crimps for secure and safe power wiring.

• Duet 3 Mainboard 6HC: Equipped with a 6-way barrier strip for Power In (VIN), OUT0 power in, and OUT0 (high current output, e.g., heated bed, max 15A, voltage can differ from main power input).
• Duet 3 Mini 5+: Includes a 4-way barrier strip for Power In (VIN), OUT0 (high current output, e.g., heated bed, max 15A).
• Duet 3 Mainboard 6XD: Features a 2-way barrier strip specifically for Power In (VIN).

Standard red/blue/yellow automotive crimp tools are suitable for crimping these terminals. Both ratchet and non-ratchet tools are available, with ratchet crimping tools generally providing more consistent and higher quality crimps.

Duet 3 mainboards utilize JST-VH series connectors for medium current outputs, commonly used for motor and general outputs:

• Duet 3 Mainboard 6HC: Used for 4-wire motor outputs (Driver 0 to 5) and OUT1, OUT2, and OUT3.
• Duet 3 Mini 5+: Used for OUT1 and OUT2.
• Duet 3 Mainboard 6XD: Used for OUT0, OUT1, and OUT2.

JST-VH crimps require a minimum wire gauge of 22AWG, with 20AWG or 0.5mm² recommended for optimal performance. Note that standard NEMA17 stepper motor wire may be too thin for direct crimping. To address this, double back the stripped wire to increase its thickness and use heat shrink sleeving over the insulation to bulk it up for a secure crimp.

A specialized crimping tool like the Engineer PA21 is needed for JST-VH crimp pins. The PA21 is designed to accommodate the longer flanges of VH crimps that grip the insulation. Use the 2.2mm jaw opening for the bare wire crimp and the 2.5mm opening for the insulation crimp. Larger ratchet crimping tools, such as the HT-225D, may also be compatible with VH series crimps. The Iwiss SN-2549 ratchet crimping tool is advertised as compatible with JST VH crimp pins and all other pin connectors currently used by Duets.

Molex KK-compatible connectors are used for all other inputs and outputs on Duet mainboards, including signal and low-power connections. For these connectors, use a manual tool like the Engineer PA-09/PA-20/PA-21 (using the 1.6mm opening for the bare wire and 1.9mm opening for the insulation) or a ratchet crimping tool like the HT-225D. The Iwiss SN-2549 ratchet crimping tool is also compatible with Molex crimp pins and all other pin connectors used by Duets.

Most Duet 3 expansion boards use the same connectors as the main boards. An exception is the Duet 3 Toolboard 1LC, which utilizes JST-PH and JST-ZH connectors to minimize board size.

JST-PH connectors can be crimped with a manual tool like the Engineer PA-09. Pre-crimped connectors are also available from electrical suppliers, simplifying the wiring process. The Iwiss SN-2549 ratchet crimping tool is compatible with JST PH crimp pins and all other pin connectors used by Duets, except JST ZH.

JST-ZH connectors (used for CAN and 1LC v1.0 headers) are very small and challenging to crimp. Duet3D provides pre-terminated connectors for these. For extending these connections, you can use hand soldering or small solder sleeves (white). Manual crimping is possible with the Engineer PA-09, requiring good eyesight and a steady hand.

4. Establishing Communication with Your Duet Board

• Begin by verifying your Duet board and connecting it to your network. Detailed instructions can be found in Getting Connected to Your Duet.
• Once network communication is established, disconnect the USB cable.
• Important Safety Precaution: Ensure NO POWER is supplied to the Duet board during all wiring procedures!

5. LED Indicators: Understanding Your Board Status

Located near the reset button on the edge of the board are several LEDs that provide status information about your Duet 3.

• These LEDs indicate the status of the 3.3V power, 5V power, 12V power, and VIN (power from your main power supply).
• In normal operation, when the board is powered and idle, the 3.3v, 5v, 12v, and Vin LEDs should be continuously lit, and the STATUS/DIAG LED should be flashing steadily.
• If the board is powered only via an external 5V supply or through USB, only the 5v and 3.3v LEDs will be illuminated.
• Additional LED indicators on the board illuminate when each high current OUT_x output is active.

The function of each LED indicator is detailed in the table below:

Label	Colour	Function
ACT	Green	Indicates activity on the CAN-FD bus (Mini 5+, 6XD)
STATUS/DIAG	Red	See detailed description below
V_FUSED	Blue	Indicates presence of fused VIN supply
12V+	Amber	Indicates on-board 12V regulator is operating
5V+	Red	Indicates 5V supply is present
3.3V+	Green	Indicates on-board 3.3V regulator is operating
USB	Red	Indicates presence of 5V power from USB (6HC)
ESP	Green	Indicates WiFi activity; flashing while searching/connecting, solid when connected (Mini 5+ WiFi version)

The red LED labeled “STATUS” (Mini 5+, 6XD) or “DIAG” (6HC) indicates the operational state of the board as follows:

LED Behavior	Meaning
Steady flashing, approximately half a second on and half a second off	Normal operation, RepRapFirmware is running correctly
Dimly glowing or completely off	Firmware has been erased (6HC, 6XD)
Pulsing from bright to dim and back again	USB bootloader is activated (Mini 5+)
Flashing three times, then off for an extended period	Firmware CRC check failed, indicating a potential firmware issue

6. Powering Your Duet 3 Board: Ensuring Stable Operation

Connect your power supply wires to the Power In screw terminals located on the barrier strip, adhering to the 3 Wiring Diagram for your specific board.

• Crucially, observe correct polarity when making power connections to prevent damage.
• WARNING: Using the included fork terminals, crimped to the power wires before insertion into the terminal block, is HIGHLY recommended. Failure to do so can lead to wire creep, loosening connections, and potential short circuits or fire hazards.
• Never tin (solder) these wires. Solder will deform and loosen over time within the screw terminal, compromising the connection.
• Avoid twisting the barrier strip while tightening screws. Hold the barrier strip steady to ensure secure connections without stressing the board.
• Re-check the terminal screws after a few days or weeks of operation to ensure they remain tight.
• Select wire gauge appropriate for the current draw of your system. The heated bed, potentially drawing up to 15A, will typically be the most demanding component. The fork terminals supplied with Duet 3 boards are designed for wires from 1.5mm² to 2.5mm² (16 AWG to 14 AWG).
• After wiring, ensure USB is disconnected (no power to the board). Test the power connection by turning on your power supply. The LEDs on the board edge should illuminate, with the 3.3V, 5V, and Vin LEDs lit.
• Immediately TURN OFF THE POWER SUPPLY after verifying power. All further wiring must be done with the Duet board completely unpowered.
• For more detailed information, refer to User manual: Choosing the power supply and User manual: Power wiring.

7. Reset Button and Firmware Erase: Board Control and Recovery

Reset Button: Rebooting Your Duet

The reset button is used to reboot the Duet board. Press it if a system reboot is necessary, for example, after making configuration changes or troubleshooting.

Firmware Erase: Advanced Recovery Option

Only erase the firmware if you are certain of the procedure and its implications. Firmware erasure is not required for normal firmware updates. Reinstalling firmware after erasure is detailed in User manual: Updating firmware.

For 6HC and 6XD boards:

• To erase the firmware, bridge the ‘Erase’ pins using a jumper, then apply power to the board. Remove the jumper before attempting to flash new firmware.
• The erase jumper clears the firmware stored on the main processor. Note that the SD card does not contain the firmware itself, only configuration files.

Mini 5+ boards: Firmware erase procedure details specific to Mini 5+ boards would be included here (consult relevant documentation if needed, though not detailed in the original extract).

8. Endstops: Setting Axis Limits for Precise Movement

Endstops are crucial for informing the printer when an axis reaches its travel limit. Duet 3 connections may differ from other controller boards, so carefully review this section and your endstop specifications before wiring, consulting the 3 wiring diagram for clarity.

• Simple microswitch endstops can be connected to any of the IO connectors on the Duet 3.
• Each IO connector provides pins for +3.3V, signal input (labeled io[#].in), GND, signal output (labeled io[#].out), and +5V.
• Duet 3 Mini 5+: IO connectors IO5 and IO6 are input-only, featuring three pins: signal input (io[#].in), +3.3V, and GND.
• For 2-wire microswitch endstops, connect one wire to GND and the other to signal input.
• WARNING: Never connect endstop wires from +3.3V or +5V directly to ground. This will create a short circuit and can severely damage your Duet board.
• For other endstop types, please refer to User manual: Connecting endstop switches for detailed wiring instructions.

9. Z Probe: Enabling Automatic Bed Leveling

• Connect your Z probe to a suitable IO connector, referencing the 3 wiring diagram for appropriate pin locations. Multiple probes can be connected if required for advanced setups.
• Wiring configurations vary significantly depending on the type of Z probe.
• Some probes may require specific IO connector capabilities such as analog input or PWM output. Consult the hardware overview for your specific Duet 3 board to verify IO connector capabilities before connecting your probe.
• For guidance on selecting a Z probe, see User manual: Choosing a Z probe.
• For detailed wiring instructions for your chosen Z probe, see User manual: Connecting a Z probe.

10. Fans: Cooling and Temperature Management

11. Duet 3 Mainboard 6HC

12. Duet 3 Mini 5+

• The 6HC offers a comprehensive set of fan outputs:

  • 3 x 4-wire PWM-controlled outputs with tacho input: OUT4, OUT5, and OUT6. Voltage selectable between VIN / 12V / external power (provide required voltage to center pin) using the OUT4-OUT6 Select V jumper.
  • 3 x 2-wire PWM-controlled outputs: OUT7, OUT8, and OUT9. Voltage selectable between VIN / 12V / external power (provide required voltage to center pin) using the OUT7-OUT9 Select V jumper.
  • 1 x VIN-voltage, always-on output for components needing constant power.
  • 1 x 12V, always-on output for dedicated 12V devices.

• PWM (Pulse Width Modulation) fan connections are used for fans where speed control is desired, such as print cooling fans.

• Always-on fan outputs are ideal for components like electronics cooling fans that need to run continuously while the printer is powered.

• PWM control compatibility varies among fans. If you encounter issues controlling fan speed, consult documentation on PWM frequency adjustments.

• Fan polarity is critical. Incorrect polarity can damage the Duet board. Always double-check the 3 wiring diagram and fan specifications.

• When using the onboard 12V regulator (i.e., 12V selected and/or using the 12V always-on output), the total 12V current draw must not exceed 800mA.

• For more detailed information on fan connections, see User manual: Connecting and configuring fans.

• The Mini 5+ provides the following fan output options:

  • 2 x 4-wire PWM-controlled outputs with tacho input: OUT3 and OUT4. Voltage selectable between VIN / 12V / external power (provide required voltage to center pin) using the OUT3&4 Select V jumper.
  • 3 x 2-wire PWM-controlled outputs: OUT5 and OUT6. Voltage selectable between VIN / 12V / external power (provide required voltage to center pin) using the OUT5&6 Select V jumper.
  • 1 x 12V, always-on output for constant cooling needs.

• PWM (Pulse Width Modulation) fan connections are for fans requiring speed control, like print cooling fans.

• Always-on fans are for continuous cooling needs, such as electronics enclosure fans.

• PWM compatibility can vary between fan models. If speed control is inconsistent, check documentation regarding PWM frequency adjustments.

• Fan polarity is crucial. Incorrect connection can harm the Duet board. Always refer to the 3 wiring diagram and fan specifications.

• When using the onboard 12V regulator (12V selected or using 12V always-on output), ensure the total 12V current draw stays below 800mA.

• For more detailed fan connection guidance, see User manual: Connecting and configuring fans.

11. Temperature Sensors: Monitoring Hotend and Bed Temperatures

Duet 3 boards directly support thermistors and PT1000 temperature sensors, which connect to the ‘TEMP’ headers on the board. Consult the 3 wiring diagram to locate these headers.

• The Duet 3 Mainboard 6HC and Duet 3 Mainboard 6XD offer four temperature inputs. The Duet 3 Mini 5+ provides three temperature inputs.
• Connect your thermistor or PT1000 sensor to one of the temperature input headers.
• Polarity is not important for thermistors or PT1000 sensors.
• While sensor placement is generally flexible, logical organization (e.g., sensor for heater0/out0 to temp0) can aid in setup and troubleshooting. You can assign any temperature input to any heater in configuration.
• For thermocouple or PT100 sensors, which require different signal conditioning, use a temperature daughterboard (see Temperature Daughterboard section below).
• For selecting the appropriate temperature sensor for your application, see User manual: Choosing temperature sensors.
• For detailed instructions on connecting thermistors and PT1000 sensors, see User manual: Connecting thermistors and PT1000 temperature sensors.

12. Bed Heater: Controlling Heated Bed Temperature

Duet 3 boards can directly power heated beds up to 15A, which is sufficient for most common heated beds. Refer to the 3 wiring diagram for your board to locate the OUT0 terminals.

• Connect your heated bed to the OUT0 terminals on your Duet board.
• Duet 3 Mainboard 6HC: provide power to the OUT0 POWER IN terminals as indicated in the 3 wiring diagram.
• Polarity is generally not critical for heaters themselves, but if your heated bed includes an integrated LED, correct polarity is needed for the LED to function.
• WARNING: Using the included fork terminals, crimped to the wires before inserting into the terminal block, is HIGHLY recommended for bed heater connections. Failure to do so can result in wire creep, loose connections, and potential fire hazards.
• Do not tin (solder) these wires. Solder can lead to connection failures in screw terminals over time.
• Securely tighten terminal screws, holding the terminal block to prevent twisting.
• Periodically check the screws for tightness, especially in the initial weeks of operation.
• For heated beds exceeding 15A or mains-powered beds, do not connect them directly to the Duet. Control these using a Solid State Relay (SSR), which the Duet can control.
• For detailed bed heater connection and configuration information, see User manual: Connecting and configuring a bed heater.

13. Hotend Heaters: Wiring Your Hotend Heating Element

Hotend heaters connect to the pin headers highlighted in yellow in the 3 wiring diagram.

• JST VH series connectors are used for medium current outputs, including hotend heaters:
  • Duet 3 Mainboard 6HC: Uses OUT1, OUT2, and OUT3 for hotend heaters.
  • Duet 3 Mini 5+: Uses OUT1 and OUT2 for hotend heaters.
  • Duet 3 Mainboard 6XD: Uses OUT0, OUT1, and OUT2 for hotend heaters.
• Crimp your hotend heater wires to the supplied JST VH crimps, insert them into the plastic shell, and then plug the connector into the appropriate pin headers on the board. Refer back to the crimping advice earlier in this guide.
• Polarity is not important for hotend heaters.
• For more detailed information, see User manual: Heaters overview.

14. Stepper Motors: Connecting Motion Axes

Duet 3 boards offer various options for connecting stepper motors. Always consult the 3 wiring diagram for your specific board model.

Duet 3 Mainboard 6HC: Features 6x JST VH 4-pin headers for stepper motors, supporting up to 6.3A peak current.
Duet 3 Mini 5+: Includes 5x Molex KK-compatible 4-pin headers for stepper motors up to 2A peak current.
Duet 3 Mainboard 6XD: Provides 6x Molex KK-compatible 6-pin headers designed for external stepper or servo motor driver connections.

Here is an example of a JST_VH connector: (Image of JST_VH connector would be beneficial here, though not provided in the original text, consider adding a generic image if possible).

15. Connecting a Display: User Interface Options

Duet 3 boards support two types of directly connected displays. Refer to the 3 wiring diagram for connector locations.

PanelDue Connection

Duet 3 Mainboard 6HC supports PanelDue connection via IO_0 only.
Duet 3 Mainboard 6XD supports PanelDue via IO_0 or the dedicated 10-pin PanelDue_SD connector.
Duet 3 Mini 5+ supports PanelDue via IO_0 or the 10-pin PanelDue_SD connector.

12864 Display Connection

Duet 3 Mini 5+ boards support 12864 mono graphics LCD displays with rotary encoders. Other Duet 3 boards do not support 12864 displays directly.

• Duet 3 only supports 12864 displays with the ST7567 controller chip.
• The 12864_EXP1 and 12864_EXP2 connectors are used to connect a 12864 display on Mini 5+.
• For detailed 12864 display connection instructions, see User manual: Connecting 12864 displays.

16. Connecting a Single Board Computer (SBC): Expanding Functionality

Duet 3 mainboards can optionally connect to a Single Board Computer (SBC) such as a Raspberry Pi to enhance functionality. Consult the 3 wiring diagram and SBC setup guide for proper connections.

• Connect an SBC to the 26-pin SBC header on the Duet 3 using the supplied ribbon cable.
• Connect the other end of the ribbon cable to the GPIO header on your SBC.
• Note the red stripe on the ribbon cable, which indicates pin 1 orientation. Ensure correct alignment as shown in the 3 wiring diagram.
• The cable can be routed around the back of the SBC if needed, maintaining correct pin 1 alignment.
• It is recommended to power the SBC separately to ensure stable voltage and sufficient current for both the Duet and SBC.
• For a comprehensive guide on setting up Duet in SBC mode, see User manual: Single Board Computer (SBC) setup for Duet 3.

17. Temperature Daughterboard: Expanding Temperature Sensing

Thermocouples and PT100 temperature sensors require a different interface than thermistors and PT1000 sensors and cannot be directly connected to the onboard temperature inputs. The 3 wiring diagram shows the TEMP_DB connector for daughterboard use.

• The TEMP_DB connector allows connecting thermocouples or PT100 sensors via a Temperature Daughterboard.
• Each daughterboard supports two additional temperature sensors of the same type (either 2x PT100 or 2x thermocouple).
• Duet 3 Mainboard 6HC and 6XD support up to two temperature daughterboards (4 additional channels). Duet 3 Mini 5+ supports one temperature daughterboard (2 additional channels).
• Thermocouples or PT100 sensors are often used for high-temperature applications exceeding the limits of standard thermistors (typically around 290°C). For sensor selection guidance, see User manual: Choosing temperature sensors.
• For detailed connection instructions, see User manual: Connecting thermocouples and User manual: Connecting PT100 temperature sensors.
• The temperature daughterboard connector can also be used to connect an accelerometer. See User manual: Connecting an accelerometer for details.

18. External 5V Input and Power Supply Control: Advanced Power Management

19. Duet 3 Mainboard 6HC

20. Duet 3 Mini 5+

• Duet boards have an onboard 5V regulator powered by the VIN input (12-36V for 6HC/6XD, 12-24V for Mini 5+).

• Ensure the ‘Int 5V EN’ jumper is in place unless you plan to use an external 5V source.

• To use an external 5V supply, remove the ‘Int 5V EN’ jumper and provide 5V power to the ‘5V IN’ pin of the EXT_5V connector, as shown in the 3 wiring diagram.

• Duet 3 Mainboard 6HC v1.01 and earlier had jumpers for powering the SBC from the Duet or vice versa. Due to current SBC power demands, separate power supplies are now recommended. 6HC v1.01a and later boards do not have these jumpers. See 6HC hardware overview: 5V for details.

• The center pin of the EXT_5V header, labeled pson, can control an external power supply. This allows the board to be powered from external 5V, with an external VIN supply switched on/off as needed. See User manual: Power wiring for more information.

• For Duet 3 Mini 5+:

  • The onboard 5V regulator is powered by VIN (12-24V).
  • Ensure no jumpers are on ‘Int 5V Disable’ or ‘5V Select’ unless using external 5V.
  • To use external 5V:
    • Connect external 5V to ‘5V IN’ on EXT_5V. Add a jumper to ‘5V Select’ between ‘5V_EXT_IN’ and ‘5V_COM’, and add a jumper to ‘Int 5V Disable’.
    • Alternatively, in specific cases, you can power the Duet from an SBC’s 5V output connected to the SBC header (not officially supported, power budget must be considered, do not exceed 1A total draw for Duet and peripherals). Add a jumper to ‘5V Select’ between ‘5V_SBC’ and ‘5V_COM’, and add a jumper to ‘Int 5V Disable’. Powering the SBC from the Duet is not supported.
  • The ‘pson’ pin on EXT_5V (shared with io4.out) can control an external power supply for VIN. See User manual: Power wiring for details.

19. Expansion: Extending Duet 3 Capabilities

Duet 3 mainboards offer several expansion options to extend their functionalities beyond the base configuration. Refer to the 3 wiring diagram for expansion connector locations.

CAN-FD Bus Expansion

• All Duet 3 boards include a CAN-FD bus connection for controlling a wide range of Duet3D expansion boards.
  • Duet 3 Mainboard 6HD and Mainboard 6XD have an RJ11 CAN-FD connector labeled CAN_OUT.
  • Duet 3 Mini 5+ has a 2-pin CAN header labeled CAN.
• CAN-FD offers high noise immunity, broad microcontroller support, and sufficient bandwidth for the demanding motion control requirements of 3D printing and similar applications.
• For a list of available expansion and tool boards, see Duet 3 family.
• For detailed information on wiring CAN connections, see User manual: CAN connection basics.

Onboard Stepper Driver Expansion (Further details on onboard stepper driver expansion, if applicable, would be added here, though not detailed in the original extract).

20. WiFi or Ethernet Module: Network Connectivity

• Duet 3 Mainboard 6HC and Mainboard 6XD are Ethernet-only. Duet 3 Mini 5+ is available in both WiFi and Ethernet versions.
• The WiFi or Ethernet module enables network connection via a web interface, crucial when not using an attached Single Board Computer.
• The WiFi module includes a green LED (LED ESP) indicating WiFi activity: flashing during searching/connecting, solid when connected.
• The WiFi module also has a U.FL external antenna connector. Ensure the external antenna is connected for optimal WiFi performance.
• The Ethernet module has two LEDs on the RJ45 housing: Link (solid when an Ethernet connection is established) and Activity (flashes during active data transfer).

21. Troubleshooting Wiring Issues: Diagnosing and Resolving Problems

If your board fails to power up after wiring, follow these troubleshooting steps:

• Verify your PSU is providing the expected voltage output.
• Check for any shorts in your wiring, particularly between VIN, 12V, 5V, 3.3V, and ground (GND).
• Inspect all fuses on the Duet board.
• Disconnect all wiring from the Duet board. Power on the board to see if it powers up in isolation. Then, reconnect wiring one connector at a time, powering down and up between each reconnection, to isolate any wiring causing a short circuit.
• Be aware that certain shorts, such as VIN to 5V or 3.3V, can cause permanent damage to the Duet. Shorts between 5V or 3.3V and ground (often due to miswired endstops) typically do not cause permanent damage but will prevent the Duet from booting. Refer to How to destroy your Duet 2, which contains relevant information applicable to Duet 3 boards as well.

Wiring Complete!

Congratulations! Your Duet 3 board wiring is now complete and ready for configuration. Proceed to the Configuring firmware guide to configure your Duet 3 system and begin printing!