PLC: Still the best mousetrap?

As a result of pressure from personal computer (PC)-based systems, vendors are offering programmable logic controllers (PLC) users open architectures that allow third-party hardware and software interfaces, a wider selection of models based on size and cost, easier Windows-based programming, and increasing use of standard networking technology such as Ethernet transport control protocol/Internet protocol. All this still comes with the high input/output (I/O) counts, speed, ruggedness and reliability traditionally associated with PLCs, and pains have been taken to be sure the new PLC-based system will mesh with the equipment users already have on the plant floor.