What does the ladder programming in PLC convert to? Does the graphic command (e.g. open contact, instruction etc.) a BASIC or C instruction, or does it compile to assembly language directly?
It's translated to mnemonic code, which is a propriarity language to Omron. This language is laid down in the system ROM in the PLC. Making a step in between (be it Basic or C) would slow down the PLC unneccesarily.