Friday, February 22, 2013

Let Study about Supervisory Control And Data Acquisition (SCADA) System

Robometricschool. In this time we want to discuss about SCADA system this this time very popular in industry. In this discussion we will show you about What is SCADA system?, Components in SCADA Systems, and Type of System Configuration.

Figure 1. SCADA System Illustration

What is SCADA system?

Before we continue more our discussion about SCADA system, firstly we will know you what is SCADA system. 
SCADA is stand for Supervisory Control and Data Acquisition. It is mean that SCADA is combination system between telemetry and data acquisition. The system consists of retrieval of information, transfer of captured data to the control center, control and decision analysis, and then the appearance of data in multiple monitors. SCADA systems are used to monitor and control the cutting edge equipment in the industry.

In here telemetry define as techniques that used to transmit and receive information or data through an intermediary. The information can be processed measurements such as voltage, speed and flow. These data are sent to other locations through the mediation of the cable, telephone or radio. The information can be sent from multiple locations with the integrated way through the system.

Beside telemetry, SCADA also consist of data acquisition, data acquisition define as methods that used to access and control information or data from the equipment to be controlled or monitored. Data are accessed and then passed to the telemetry system and ready to send to a different location. The data can include information in digital or analog form collected by sensors such as flow-meter, ammeter and others. He can also be data to control devices such as actuators, relays, valves, motors and others.

Beside SCADA we also find other terms, this terms is DCS. What is DCS and difference with SCADA system? in here DCS stand for Distributed Control Systems. DCS also used in industry and placed in good and closed place. DCS using the communication medium with high speed, such as local area network (LAN) and there are a number of closed-loop control of the system.

DCS will deference with SCADA because SCADA covers the system with a larger area, and have some tissues such as radio and telephone communications and closed loop control is not very important in this system.

Components that used in SCADA System

When we tell about SCADA, this system has more than 4 components that used. The components are usually used in SCADA system likes filed instrumentation, remote stations, communication networks, central monitoring station.
Figure 2. Components of  SCADA System

  1. Filed Instrumentation is a component that usually a sensor or actuator that is connected directly to the equipment. He produces analog and digital signals are monitored at the remote stations. Signal also conditioned to assure the compatibility between the input and output on the Remote Terminal Units (RTUs) or Programmable Logic Controller (PLC) on the Remote Station.
  2. Remote Station is a component that installed on the remote plant or equipment monitored or controlled by the central host computer. It can be a Remote Terminal Units (RTUs) or Programmable Logic Controller (PLC).
  3. Communication Networks is component that used as intermediaries to transfer information from one location to another. Can be a telephone, radio or cable.
  4. Central Monitoring Station (CMS) is the location of the master or the host computer. He may consist of several control center using Man Machine Interface (MMI) program to monitor certain types of data needed for the operation.

Types of System Configuration

To complete you knowledge in SCADA system, in here we will give you about types of system configuration. There are two types of system configuration that usually used in SCADA system.

Figure 3. Point to Point Configuration
Figure 4. Point to Multipoint Configuration
  1. Point to Point Configuration. This configuration is the telemetry configuration system that very simple. The data here are exchanged through two stations. The station is used as master and the other as the slave. An example is the two RTU setup: one for the reservoir or tank and other water pumps at different locations. By the time the tank is nearly empty, the tank RTU will send EMPTY RTU command to another and when the tank is full, tank FULL at the RTU will send a command to the RTU pump to stop the motor. Please see figure 3 above. 
  2. Point to Multipoint Configuration. This configuration used if the equipment is used as a master unit for multiple slave units. Master is usually the primary host and placed the control room and the remote slave units in the field. Each slave has a unique address or ID number. See figure 4 above.


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