4diac is described as 'Eclipse 4diac provides an open source infrastructure for distributed industrial process measurement and control systems based on the IEC 61499 standard' and is an app in the development category. There are four alternatives to 4diac for Windows, Linux and Mac. The best 4diac alternative is CODESYS. It's not free, so if you're looking for a free alternative, you could try CODESYS or ClassicLadder.
CODESYS is the leading manufacturer-independent IEC 61131-3 automation software for engineering control systems. It is used to program many hundreds of different controllers, PLCs, PACs and other automation system, even via an Industry 4.0 interface.
The programming tool logi.CAD 3 is built on eclipse and its focus is on efficient and effective programming of controllers according to IEC 61131-3 for every kind of size - from Micro-Controllers to Multi-Core Industry PCs.
LOGO! Soft Comfort is software for programming simple Siemens LOGO! PLCs. Programming is done in one of two graphical programming languages - FBD (Function Block Diagram) or LAD (Ladder Diagram).
An open source project to have a free ladder and sequential (grafcet) programming software coded in C language (to be used for educational as PLC Simulator, training, in Software PLC on PC computers or embedded platforms, ...).
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