CODESYS - CODESYS - the IEC 61131-3 programming system.
FreeCAD - An open-source parametric 3D modeler
ETAP - ETAP is a full spectrum analytical engineering software company specializing in the analysis, simulation, monitoring, control, optimization, and automation of electrical power systems.
SketchUp - 3D for Everyone
4diac - Eclipse 4diac™ provides an open source infrastructure for distributed industrial process measurement and control systems based on the IEC 61499 standard.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.