I recently was shown the CodeSys environment for a PLC, and I could not help but notice that the “structured text” as it is called (IEC 61131-3) looks very much like the VHDL I have used in the past for FPGAs. This is more of a question of curiosity. Is structured text inspired by VHDL syntax or is it the other way around? Can someone break this down for me? VHDL is a hardware description language, and the logic is eventually synthesized into a transistor representation. Obviously, this is not the case for a PLC, but because the PLC is often used for establishing multi-module state machines, it makes sense why the syntax of hardware description languages are similar. In addition to my question on origin, I am also curious of the differences between structured text and vhdl syntax?