Saturday, 11 December 2010


There are two elements in SCADA applications, namely:1. Processes, systems, machines that will be monitored and controlled - can be a power plant, irrigation system, computer network, traffic system of traffic lights or whatever;2. A network equipment 'smart' interface to the system via sensors and control outputs. With this network, which is a SCADA system, allowing you to monitor and control componentscomponents of the system.
You can build SCADA systems using different technologies and different protocols.
You can use the SCADA to manage a variety of equipment.Typically, SCADA is used to perform complex industrial processes automatically, replace human labor (could be because it is considered dangerous or impractical - is a logical consequence of layoffs), and usually a process that involves factors more control, these factors motion-control more quickly, and so forth, where control by humans become uncomfortable again.For example, SCADA used around the world for example to ...• Producers, transmission and distribution lines: SCADA is used to detect the amount of current and voltage, the operational monitoring of circuit breakers, and to turn off / turn on the power grid;• Storage and distribution of water: SCADA is used for monitoring and regulation of water flow rate, high reservoir, pressure pipes and various other factors;• Buildings, facilities and environment: facilities manager to use SCADA to control HVAC, refrigeration units, lighting, and security systems.• Production: SCADA systems manage inventory of components, set up automated or robotic tools, monitoring processes and quality control.• electric railway transportation: use SCADA monitoring and control can be performed electrical distribution, automation of railway traffic signals, railway track and find the location, controlling cross the railway and so forth.• Light traffic: SCADA monitor traffic lights, controlling the rate of traffic, and detect-sinyals the wrong signal.
And, of course, there are many more potential applications for SCADA systems. SCADA is used in almost all industrial projects and public infrastructure.
The point SCADA can be used in applications that require ease of monitoring as well as control, with a variety of media and communications interfaces available today (eg, computer, PDA, Touch Screen, TCP / IP, wireless, etc.).
Why also pake SCADA?
Try now think about the responsibility or your job at the company, deals with all kinds of operations and parameters that ultimately affect the production:• Do you need a Power Supply of equipment, a controlled temperature, humidity environment that is stable and never die?• Do you need to know - in real time - the status of various components and equipment in a large complex system?• Do you need to know how changes in inputs affect outcomes?• What equipment you need to control - in real time - from a distance?• Do you need to know where the fault / damage within the system that affect the process?
Ask some of these points before, I'm sure you'll be able to estimate where you can apply the SCADA. It may be that you will say again "Keep doing? So What? ". What do you really want to know is how real results you can expect to apply the SCADA?Here are some things you can do with SCADA System:• Accessing the quantitative measurement of important processes, either directly then or over time.• Detect and correct errors quickly.• Measure and monitor trends over time.• Finding and eliminating bottlenecks (bottlenecks) and waste (inefficiency).• Controlling the processes of the larger and more complex with trained staff are a little more.
 In essence, a SCADA system gives you the flexibility to set maupuan configure the system. You can place the sensors and control at each critical point in the process that you signed (along with SCADA technology for better, you can put more sensors in many places). More and more things that can be monitored, the more details you can see the operation, and it all works in real-time. No matter as complex as any process that you handle, you can see the process in large scale operations and small, and you can at least do a search if something goes wrong and at the same time improving efficiency. With SCADA, you can do many things, the fare is cheaper and, of course, will increase profits!
 Example SCADA Architecture
How SCADA works?
A SCADA system has 4 (four) functions, namely:1. Data Acquisition,2. Data communications network,3. Peyajian data, and4. Control (process)
These functions are supported entirely through 4 (four) SCADA components, namely:1. Sensors (both analog and digital) and control relays directly related to various kinds of actuators on the controlled system;2. RTUs (Remote Telemetry Units). Represents units "computer" small (mini), meaning a unit that is equipped with an independent system such as a computer, placed on the location and certain places in the field. RTU acts as a local data collectors obtain data from sensors and send commands directly to the equipment in the field;3. SCADA master unit (Master Terminal Unit - MTU). If this is a computer that is used as a processing center of the SCADA system. This master unit provides the HMI (Human Machine Iterface) for the user, and automatically set the system in accordance with the inputs (from sensors) received;4. Communication network, a medium that connects the SCADA master unit with the RTU-RTU in the field.
The simplest SCADA systems that might be encountered in the world is a single circuit that tells you of an event (event). Imagine a factory that produces knick-knacks, each time a product is successful knick-knacks, will activate a switch which is connected to a lamp or an alarm to notify that there was a knick-knacks that successfully created.Of course, SCADA can do more than just these simple things. But the principle is the same, a full-scale SCADA system can monitor and (once) to control the process a much larger and complex.
In reality, you need a monitor that is far more numerous and complex than just a machine that produces a product (like the previous example). You may require monitoring of hundreds to thousands of sensors spread throughout the factory area. Some sensors are used for the measurement of inputs (eg, rate of water into the reservoir), and several sensors used for the measurement of outcomes (pressure, density, density, etc.).
Some sensors can perform measurements in a simple event that can be detected using a switch ON / OFF, input such as is referred to as a discrete input or digital input. For example, to find out whether an appliance is working (ON) or not (OFF), konveyornya already road (ON) or not (OFF), the engine is already stirring (ON) or not (OFF), and so forth. Several other sensors that can perform complex measurements, where the numbers or specific values that are very important, the input is called an analog input, can be used to detect changes on a continuous basis, for example, voltage, current, fluid density, temperature, and so forth.
For most analog values, there are certain limits as defined previously, both the upper and lower bounds. For example, you want to maintain the temperature between 30 and 35 degrees Celsius, if the temperature is below or above these limits, it will trigger the alarm (both light and / or the sound of it). There are four alarm limits for analog sensors: Under Major, Minor Under, Over Minor, and Major Alarm Over.
From the simple example of plant knick-knacks, which referred to 'network' in that case is just a cable that connects the switch with the panel lights. In fact, you often want to monitor various parameters derived from a variety of sensors in the field (factory), so you need a communication network to do so.Initially, SCADA perform data communication via radio, modem or serial cable lines special. Currently SCADA data can be transmitted via an Ethernet network or TCP / IP. For security reasons, computer networks for SCADA is a local computer network (LAN - Local Area Network) without having to expose critical data on the Internet.
SCADA communications managed through a protocol, if the days of old used a special protocol in accordance with its SCADA manufacturers, now there are a few standard protocols have been defined, so nothing to worry about compatibility issues komuninkasi again.
Since most sensors and control relays only electrical equipment that is simple, these tools can not produce or translate the communication protocol. Thus, RTU needed a bridge between the sensors and SCADA networks. RTU convert sensor inputs to the relevant protocol format and sends to the master SCADA, RTU but it also accepts commands in the format of the protocol and provide the appropriate electrical signal to the relay controls are concerned.
 Figure Example of Network SCADA System
For the case of our trinkets factory, the only display is a lamp that will light when the switch is activated. Yes, of course, reality can be tens to hundreds of lights, imagine who would you want to watch these lights, decorative lights emangnya? Not right?SCADA System for reporting status of various sensors (both analog and digital) through a special computer that had made its HMI (Human Machine Interface) or its HCI (Human Computer Interface). Access to the control panel can be done locally or through the website. Even currently available control panels that touchscreen. Note the examples of pictures and explanations in the CASE STUDY.
 Figure Example of access through the website SCADA CONTROL
Unfortunately, in this example we trinkets factory there is no element of control. All right, we add a control. For example, the operator now also has a button on the control panel. When he clicks on the button, then the switch at the plant will also be ON.Okey, if then you add all the controls into the plant SCADA system through the HMI it, then you get a full control over your computer, even using sophisticated SCADA (nearly all SCADA software products are now sophisticated) can be automated control or automated process, without involving human intervention. Of course, you still can manually control it from the station master.
Of course, with the help of SCADA, process can be more efficient, effective and increase company profit.
How to evaluate the system and Hardware SCADA?
Okey, now the problem is the instructions how to select and sort out the good SCADA system. Moreover, SCADA systems you will use up to 10 to 15 years to come, surely you should look for products that are well-known reputation. But this will impact on investment should be done, a product with reliable and renowned reputation certainly cost much more than the new SCADA products is currently starting a lot of popping.There are some important things you need to consider, among other things:• You can spend the future of the plant with excess costs that are not necessary;• Sometimes after spend a very large, eventually you just get a system that is less or even not meet what is desired;• Or perhaps the current system really needs, but not for future development.
The brief notes about the Sensor and Networking
Sensor and relay control is an important component. Of course, there are several sensors that are better than others, but the availability of the datasheet for a sensor will help you identify more details of the relevant sensors, so you can choose which is best.A network (LAN / WAN) are based on TCP / IP is the network that is easy to use, and if your plant is not yet all have a network, the transition to the LAN network may be the company's long-term goals. But you do not need to immediately implement all of the LAN network to benefit from the use of SCADA. SCADA systems will support both your old network and LAN network, so you can make the transition gradually.
Here I have to say a few pointers (from experience and several references from online and offline) in building a SCADA system, especially the selection problem RTU and MTU.
What you need to consider in choosing a SCADA RTU
SCADA RTU you must be able to communicate with all kinds of equipment at the plant and can withstand the wide range of industrial conditions (heat, cold, pressure, etc.). The following checklist for selecting a quality RTU:• The capacity sufficient to support a variety of equipment in the plant (within the scope of the desired SCADA), but no more than necessary. Do not until you buy the RTU with excess capacity so that ultimately will never be used, this is a waste.• Construction of a resilient and ability to withstand extreme temperatures and humidity. It's obvious right? If not resilient and can not survive for any pair of these RTU? It could be the result of measurement to be inaccurate and broken equipment.• Power supply safe and abundant. SCADA systems often have to work a full 24 hours every day. RTU should be used to support the use of power from the battery, ideally, there are two sources of power supply (electricity and batteries).• Port communication is sufficient. The network connection is as important as the power supply. The second serial port or internal modem can keep RTU networks remain online even when it is damaged or fails. In addition, the RTU with a variety of communication ports to support the migration strategy LAN.• nonvolatile memory (NVRAM) for storing firmware. NVRAM can store data even if power supply is turned off. New firmware (the modification, etc.) can be downloaded into the NVRAM storage over a network, so the ability of RTU will always be up-to-date (renewable) without having to visit the respective RTU location.• intelligent control. Sophisticated SCADA system currently can do on its own control in accordance with the programs or settings that are included, especially in response to a variety of input sensors.This is clearly not necessary for all applications, but offers ease of operation.• Real-time clock (real-time clock). for printing date / time to report promptly and accurately;• watchdog timer which ensures RTU can start over again after a power failure (power failure).
 A typical RTU arsitetur
What you need to consider in choosing a SCADA MTU
SCADA master or MTU must be able to display various information in a form familiar to its users or operators. Some things to note relating to SCADA MTU:• Flexible, in response to the sensor can be programmed. Find a system that provides an easy tool to program the soft alarm (incident reports that the complex is a combination of sensor inputs and the statement date / hour) and soft control (response to sensors that can be programmed).• Working full 24 / 7, via SMS alerts (pagers) and email notifications automatically. You do not need to hire people to observe the monitoring board 24 hours a day. If the equipment requires human intervention, then the system will automatically send alerts via SMS or email to the person in-charge concerned.• Display detailed information. Surely you want a system that displays in your daily language (English, Indonesian, etc) a clear and simple, with a complete explanation of the activity is happening and how you should handle or respond.• Filters for the alarm interrupt (not necessary). Alarms that interfere will make the staff to be not sensitive enough to alarm reporting, and they began to believe that all alarms are alarms disturbing. Eventually they will stop responding to all alarms including critical alarms (alarms really have to get attention). Use SCADA which can filter and sort out alarms which are disturbing and critical.• The ability of future development. A SCADA system is a long term investment (10 to 15 years). So you need to ensure the ability of SCADA for development in a period of 15 years.• Appropriation of that range. SCADA systems are both support multiple backup masters, in some locations. If the primary SCADA master fails, the second master in the network will take over automatically, without any interruption of monitoring and controlling functions.• Supports multiple protocols and equipment types. If the past SCADA dbuat only to certain protocols that are closed. Merupakn single vendor solution is not a good idea - often vendors no longer provide support for their products. Support for a variety of open protocols that will safeguard your SCADA system of non-planned obsolescence.
 A typical architecture MTU


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