FreeCAD - An open-source parametric 3D modeler
CODESYS - CODESYS - the IEC 61131-3 programming system.
SketchUp - 3D for Everyone
RobotStudio - RobotStudio increase the profitability of your robot system by letting you perform tasks such as training, programming, and optimization
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
4diac - Eclipse 4diac™ provides an open source infrastructure for distributed industrial process measurement and control systems based on the IEC 61499 standard.