The DCS concept increases reliability and reduces installation by localizing control function near the process plant, with remote monitoring and supervision. DCS are dedicated system used in manufacturing processes that are continuous or batch oriented. The processor receive information from input modules process the information and decide control actions to be signaled by the output modules. The field input output can be analog signal e.g. 4-20mA DC current loop or 2 state signals that switch either ‘on’ or ‘off’ such as relay contact or semi-conductor switch.