Open Source Designs



Waltech LadderMaker Ladder Logic Software


WLM screeshot


Running on Win 10 by Julian Columbo of São Paulo.  video-icon.png

Click for a video, v. 107a video-icon.png

Click for an earlier video video-icon.png

Version 105 video video-icon.png


  • Easy to learn and use Graphical Programming.
  • Written in Python
  • Linux and Windows packages available
  • Integrated USB uploading to hardware

Compatible hardware:

  • Waltech PLC V2.
  • Arduino Uno.
  • Arduino Mega
  • Arduino Nano


5/12/2015 version 110a

Fixed upload to new Mega bootloader.

More than one ADC can be used now.  Multiple parallel circuits warning. 

↓ LadderMaker Python Source v.110a 

11/08/2014 version 1.07a

Added Arduino Nano support. PWM, ADC elements available on Arduio Uno and Nano. Note: There are fewer input and output pins now to make room for PWM and ADC. 

Some bugfixes. Thanks to Adam J. and Mark W.

↓ LadderMaker Python Source v.107a 

↓ LadderMaker for Windows v.107a

7/21/2014 version 1.05a

More elements added and Arduino Mega2560 support.

↓ LadderMaker for Windows v.105a

↓ LadderMaker Python Source v.105a 


Please read [this blog post.]

Unzip download. No installation required.

Running Python Source: Browse to Program folder, open a terminal, and run Requires Python 2.7 and pyQt4. Must be run in a terminal for USB testing and upload to work. 

LadderMaker Linux Boot Disk iso. Download, burn iso to a CD, and boot to the CD. Laddermaker folder is on the desktop.

Check the version. If a later version of the Source is available here, download it, and replace the Program and Helpers folders in MyApplications/WaltechLadderMaker folder

Windows Build: Requires no other components. Browse to 'program' folder and double click main.exe.  Change in Device Manager if needed.  Tested on Windows 7. 

Ladder Maker for windows package does not show the element icons on some Windows installations.  Try installing VC++ redistrubutable 2008. VC++_Link.  

An alternate is to use the python source, and install Python, Qt, and PyQt:  XP Links here:     Python 2.7   QT      PyQT  

Mac: The latest versions need to be tested and adjusted for Mac usage, so for now we are recomending using a virtual machine such as VirtualBox, and running Linux or Windows.

For version 0.92 and older only: download Ladder Maker Source.  Install Xcode and MacPorts.  Run the following: 

  • sudo port selfupdate
  • sudo port install py27-pyqt4 (wait long time)
  • sudo port install avr-gcc
  • sudo port install avr-libc
  • sudo port install avrdude

Introduction to Ladder Logic: On Slideshare- LINK


PLC-style DIO Board Version 2.


 DIO board v2


  • Main board has 4 inputs and 4 outputs.
  • Optically isolated inputs and relay outputs.
  • Add  2 additional I/O boards for a total of 12 inputs and 12 outputs.
  • Uses an on board programmer, USBTINY
  • Compact and all in one
  • Choice of 3 or 10 amp relays
  • Uses Waltech LadderMaker software
  • 2 sided board, no internal layers
  • Source code,  and schematic open licence



Open design digital wideband oxygen sensor controller


Several years ago we decided to offer an Open Design. We chose to build a controller for a wide band oxygen sensor because there didn’t seem to be a fully open microprocessor based design available on the Internet. After studying what we could find on the subject, we chose to investigate what can be achieved with a simple circuit and a common microcontroller.

With the information presented here, you can build a controller circuit that will function, and can be a useful tuning or diagnostic tool. We encourage building this circuit as an educational tool, or as a starting point to an improved version.

 Click here for the WBO2 page.