Command and control elements

The machines and systems connected to the automation system are managed by command signals sent to the controller by the command elements on the control panels. Command elements are various instruments used in daily life such as buttons, switches and rheostats. Command elements send command signals to the controller. When the controller confirms that the necessary conditions are met to fulfill the given command, it transmits this command to the required actuators. Operator monitors the realization of the commands he/she sent by observing the signals coming from the sensors and reaching the monitors via the controller. The operator analyzes and interprets these impressions and decides for the situation and the actions to be taken and implements it. Monitors are elements that show digital and/or analog information such as pressure, temperature, flow, and velocity that come to them through sensors and controllers. Control elements are operated directly by hand or, may be embedded to the controller software. Control elements are the elements that reflect the incoming information to the monitors as image, sound and light. Briefly, the two basic elements of the automation system are the command-and-control elements and their command-and-control signals (Figure.1).

Figure.1 Typical command and control elements on a control panel