Maybe we are arguing semantics here... but read up about the Beckhoff TwinCAT system and how it works. I would say Beckhoff systems are both an IPC and a PLC in

Maybe we are arguing semantics here... but read up about the Beckhoff TwinCAT system and how it works. I would say Beckhoff systems are both an IPC and a PLC in one. Beckhoff system run two OS'es... the PLC runtime is hard real-time and runs at the chipset level (so even if the windows or freeBSD crashes the PLC still runs). You program the PLC using IEC-61131 languages (structured text which sort of between BASIC and Pascal, ladder logic, sequential function chart, cyclical function chart, etc.) and also have the option to run C/C++ code (with no dynamic memory allocation). For what it is worth, newer Omron PLC's run PLC code on top of QNX, B&R automation uses a very similar approach to Beckhoff. Overall, the B&R and Beckhoff PLC's are, I think, under-appreciated.