PLC emulator for programmable controllers. Our PLC emulator is based on a SIEMENS PG 605 programming device in STEP 5. With it, PLC programs can be written, tested on simulation basis, loaded, saved, changed, printed and output as FBD (function plan with logical gates). Included are an editor, an interpreter and FBD generator. All commands are fully implemented in the Siemens S5 standard.