Sensors

Sensors are termed as the ears and eyes of control system. The major uses of sensor are to provide real time information for directly controlling procedure as well as provide information for data logging purposes. For instance, a sensor may be used to provide a count of the daily unit produced off a specific manufacturing line. Sensor technology discovers a great use in the field of CIM, process control, laboratory testing, and other areas commercially available. As illustrated in Figure 4, sensors might be categorized in two types:

1. Discrete and

2. Continuous.

A discrete event sensor or on/off sensor provides the state depends on the occurrence of some external event. The event might be passing of a part by a point along a conveyor or the movement of a mechanical device beyond some prescribed restriction. The discrete event sensors just give the knowledge of two states depends on the condition being sensed. In the first instance, the part is either present or not present. In second case, the device is either in the prescribed limit or it is not.