Connects to the serial interface of a Kayo-A4 pick-and-place machine, and provides a USB interface with an onboard GCode interpreter that translates messages into the format necessary for the Kayo's motion controller.
This allows Kayo machines to be controlled using OpenPnP.
You will need a computer running OpenPnP, with sufficient USB ports to handle the connections to the controller, cameras, etc. This is a normal OpenPnP requirement so check the OpenPnP docs for details.
The hardware adapter portion of the project can minimally be built with an ESP8266-based dev board such as a Wemos D1 Mini and some cables.
A dedicated ESP32-S3 hardware design is provided, which includes additional features such as a CAN bus interface to integrate with other devices on the production line.
Adapter Board Features
- USB-C socket for connection to host computer running OpenPnP
- ESP32-S3 MCU
- 3-way 3.81mm screw socket for connection to Kayo serial cable
- Onboard USB hub with 2 spare ports exposed
- RGB LED for status display
- Connections for external RGB LED strip for traffic-light status display etc
- 128x32 OLED
- Piezo for alarms
- CAN bus interface with optional CAN termination
- Can be powered via USB if only a serial connection + USB is required
- Can be powered at 12V via screw terminals to pass power on to CAN bus
- Can be powered at 12V via CAN bus if another device on the bus is powered
Kayo machines are supplied with a Windows PC running their proprietary control software, which is connected to a motion controller mounted inside the chassis via a serial connection. The serial port is connected using a 3-way 3.81mm pitch pluggable screw terminal, which includes signal GND, TX, and RX:
- Logic voltage: 3.3V
- 115200 8N1
The protocol converter uses the axes listed below. OpenPnP needs to be configured to use these same axes.
- X: horizontal left/right
- Y: horizontal forward/back
- Z: virtual vertical axis for top camera, which doesn't physically move vertically
- A, B, C, D: rotational axes for nozzles 1-4
- I, J, K, L: z (vertical) axes for nozzles 1-4
Kayo "home" is in the top right corner at coordinates "0,0", so the working area is negative coordinates relative to that. That may sound confusing at first but it works out quite nicely in practice. For example, a typical board origin when clamped on the conveyor could be at something like "-155, -453".
Nozzles are at a 0 position when fully retracted (raised) and typically descend to approximately -9.8mm to -10.1mm to touch the surface of a clamped PCB or feeder pickup location.
| Code | Meaning |
|---|---|
| G28 | Reset and home |
| G0 Xpos Ypos | Move X & Y to the defined absolute position in mm, eg: "G0 X-23.4 Y-18" |
| G0 Ipos | Move specified nozzle vertically to absolute position in mm, eg: "G0 I-7.6" to send nozzle 1 to -7.6mm (I=n1, J=n2, K=n3, L=n4) |
| G0 Apos | Rotate specified nozzle to an absolute angle in degrees, eg: "G0 A48" to send nozzle 1 to an angle of 48 degrees (A=n1, B=n2, C=n3, D=n4) |
Note: the Kayo motion controller has an interlock on X/Y movement with Z axis displacement. You CANNOT move the machine in X or Y axis while holding a nozzle partly extended. It handles this by automatically retracting all nozzles whenever it gets an X/Y movement command.
This means that you can't use advanced motion planning in OpenPnP, and you also can't assume that you know the Z axis position of any nozzle. If you move the head in X/Y, all Z axes will be immediately zeroed with no warning.
| Code | Meaning |
|---|---|
| M2 Nnoz | Close vac and open blow on specified nozzle, eg: "M2 N2" |
| M3 | Close vac and blow on all nozzles |
| M4 Nnoz | Open blow on selected nozzle, eg: "M4 N3" |
| M5 Nnoz | Close blow on selected nozzle, eg: "M5 N2" |
| M6 Nnoz | Open vac on selected nozzle, eg: "M6 N1" |
| M7 Nnoz | Close vac on selected nozzle, eg: "M7 N1" |
| Code | Meaning |
|---|---|
| M2 | Reset conveyor |
| M21 Nwidth | Adjust conveyor to specified width + configured margin, eg: "M21 N93.4" |
| M22 | Ingest a PCB and clamp it in position |
| M23 | Unclamp PCB and move it to the exit location |
| M24 | Start conveyor |
| M25 | Stop conveyor and drop pin |
| M26 | Engages the stop pin |
| M27 | Clamp a PCB on the conveyor |
| Code | Meaning |
|---|---|
| M30 | Turn off camera lights |
| M31 Sbrightness | Turn on fast camera light at specified brightness %, eg: "M31 S15" |
| M32 Sbrightness | Turn on precision camera light at specified brightness %, eg: "M32 S46" |
| Code | Meaning |
|---|---|
| M114 | Report position |
| M115 | Report firmware type and version |
| Code | Meaning |
|---|---|
| M600 Nfeeder | Open specified feeder, eg: "M600 N12" |
| M601 | Close feeders (no need to specify) |
Note: The Kayo motion controller only ever allows a single feeder to be open at a time. If you have one feeder open and then send an open command for a different feeder, the first one will be closed automatically.
There is no command to close a specific feeder. M601 closes whatever was last opened.
| Code | Meaning |
|---|---|
| M99 Nnoz Ssteps | Send microsteps to specified nozzle rotation stepper, eg: "M99 N1 S1234" |
I have been unable to connect the 5 factory bottom cameras (1 x precision camera and a 4-way high-speed camera array) to OpenPnP on either Ubuntu or MacOS. You may have more success on Windows: please let me know!
On my machines I have unscrewed the 4-way camera array and tucked it away under the feeder manifold, and also removed the precision camera. I replaced that with an ELP Mini 720p OV9712 USB industrial camera with a 6mm lens, using a 3D-printed camera mount and a lens spacer to change the focal length.
This particular camera is very commonly used for OpenPnP so it's a well-known and well-supported device.
1. Remove light bracket and the original camera:
2. 3D-print mounting plate and lens spacer:
3. Remove lens from ELP camera:
4. Reattach lens with 6mm M2 bolts with spacer:
5. Attach mounting plate with M3 bolts:
6. Pass cable through mounting plate and screw camera on with 2mm self tappers:
Finally, reinstall the light bracket and then do the usual focus and camera calibration process in OpenPnP.
The top camera has an analog output. I connected it to an analog-to-HDMI converter, which then goes to a cheap HDMI-to-USB converter so that it appears as a webcam under Linux and can be accessed by OpenPnP.
You can use the original discard tray behind the PCB area, but with the 4-camera array removed there is an ideal location for a discard tray right behind the camera location. This allows a very short movement to the tray if the vision pipeline rejects the parts.
I have designed a discard tray holder that has a 1x2 Gridfinity mount in the base, and holes to attach it to the T-slot front rail using T-nuts and M3 bolts:
You can use a regular 1x2 Gridfinity tray. I've included a design for a 1x1 tray with the height set to match the mounting rail. OpenPnP currently only supports a single discard location, but support for multiple trays is in development:
The control protocol for the Kayo motion controller uses 8-byte messages in both directions, with no terminator. Message boundaries are discovered by watching for a leading character, tracking the number of bytes received, and timing out as a fallback to handle incomplete messages or errors.
The protocol is embodied in the source code. Docs to be added here later.
The "Hardware" directory contains the PCB design as an EAGLE project. This can be imported into KiCAD, or opened natively using Fusion360.
The "Firmware" directory contains example firmware as an Arduino project.
- Jonathan Oxer [email protected]
Heavily inspired by Glen English's Python-based UI for the Kayo, in particular his work decoding the message format used by the factory software.
Copyright 2022-2025 SuperHouse Automation Pty Ltd www.superhouse.tv
The hardware portion of this project is licensed under the TAPR Open Hardware License (www.tapr.org/OHL). The "license" folder within this repository contains a copy of this license in plain text format.
The software portion of this project is licensed under the Simplified BSD License. The "licence" folder within this project contains a copy of this license in plain text format.