PLC vs. PAC vs. IPC

It is important to know features, limits, and compatibilities for selecting the right controller: programmable logic controller (PLC), programmable automation controller (PAC), or industrial PC (IPC). Choosing correct control platform in the beginning increases chances of the project's success. A system integrator can help with controller selection. Control systems today are more powerful, more flexible, easier to program and easier to communicate with. Many companies making control systems and multiple lines can cause paralysis when determining the right make and model of controller. With a little understanding of different features and limitations, an engineer can make a decision for choosing among programmable logic controllers (PLCs), programmable automation controllers (PACs), or industrial PCs (IPCs). Controllers relays Till late 1960s control systems had relays controlling discrete functions and loop controllers controlling analog functions. This posed many challenges including consumption of large spaces for relays, expensive changes and often monumental troubleshooting efforts. In early 1970s PLC was created and industry began to use it widely replacing relay systems. At first PLCs were large (though smaller than walls of relays), and programming was done with dedicated terminals and limited instructions. In late 1970s distributed control systems (DCSs) began replacing loop controllers and centralizing process control environment. DCSs consist of multiple input/ output racks located close to end control devices and PC-based visualization and engineering station. In early...