PLC and DCS: The Heart of Process Controls
The primary devices that are used in a process control system are Programmable Logic Controllers better known as PLCs in short. PLCs are the best bets for controlling machines with several discrete devices such as motor starters, limit switches, and the likes of them, which are often involved in automation process like material handling, state machines, sequencing, status reports etc.
Distributed Control Systems, commonly abbreviated as DCS, are central control systems, which are good at controlling analog devices; thereby aiding in process control.
In a manufacturing setup, feedback from different sensors tendering to many processes are given to a bank of PLCs. Each process has a separate set of PLCs and the output of these which contain information regarding the status at the shop floor is given to the DCS. PLC is just a controller and DCS is a central controller with a MMI [Man Machine Interface]. Corrective controls are input to the DCS, which is given to the PLC and thereafter sent to the individual control devices.
Modern PLCs & DCSs have enormous capability in a plant automation setting. There is good deal of difference in the capabilities of DCS as well as PLCs. DCS offers an integrated development environment which provides more powerful remote process control computers. DCS also functions as a supervising control which maintains quality at the desired level intended for the product.