1. CISSP Common Body of Knowledge Review by Alfred Ouyang is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA. Overview of Monitoring and Control Systems

2. Real Time System A real-time system has been described as one which "controls an environment by receiving data, processing them, and returning the results sufficiently quickly to affect the environment at that time.” The term "real-time" is also used in simulation to mean that the simulation's clock runs at the same speed as a real clock, and in process control and enterprise systems to mean "without significant delay".

3. Monitoring and Control Systems Monitoring: - computer system takes information from the sensors compares the data with stored values - warns/informs the user of status either by read outs or alarms Control: - computer system takes information from the sensors - compares the data with stored values - sends signals to devices to open/close, on/off etc. - output from system can affect next input

4. Sensors A sensor is a transducer whose purpose is to sense (that is, to detect) some characteristic of its environments. It detects events or changes in quantities and provides a corresponding output, generally as an electrical or optical signal For example, A mercury-in-glass thermometer is also a sensor; it converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube.

5. Acutators An actuator is a type of motor That is responsible for moving or controlling a mechanism or system. It is operated by a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion. An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.

6. Different Types of Control Systems Logic Control On-Off Control Linear Control Proportional Control PID Control

7. Logic Control Logic controllers may respond to switches, light sensors, pressure switches, etc., and can cause the machinery to start and stop various operations. Logic systems are used to sequence mechanical operations in many applications. PLC software can be written in many different ways – ladder diagrams, SFC – sequential function charts or in language terms known as statement lists.

8. On-Off Control A thermostat is a simple negative feedback controller: when the temperature (the "process variable" or PV) goes below a set point (SP), the heater is switched on. Another example could be a pressure switch on an air compressor. When the pressure (PV) drops below the threshold (SP), the pump is powered. Refrigerators and vacuum pumps contain similar mechanisms operating in reverse, but still providing negative feedback to correct errors.

9. Linear Control Proportional Control When controlling the temperature of an industrial furnace, it is usually better to control the opening of the fuel valve in proportion to the current needs of the furnace. This helps avoid thermal shocks and applies heat more effectively. PID Control

10. Applications Monitoring and Control Hospitals (monitoring patient’s vital signs), Chemical and nuclear plants (monitoring key parameters), Burglar alarms (monitoring for intruders), etc. traffic lights (controlling the sequence of lights to maintain optimum traffic flow), chemical and nuclear plants (opening and closing valves, safety systems

11. CISSP Common Body of Knowledge Review by Alfred Ouyang is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA. Thank You - 11 -