Tuesday, November 17, 2015

Take Benefits DCS and PLC/SCADA - a Comparison in use to Acquire Control Systems as Required




The use of PLC / SCADA is often regarded as the most sophisticated control systems solutions today. Though there are other control systems such as DCS currently has a feature and has several advantages compared PLC / SCADA. At the past time, DCS was popularly used in the design of the control system, but with the SCADA control method, the use of DCS had dropped drastically. Along with the development of technology, DCS is also growing with a variety of features and services that can be obtained. For users of SCADA or DCS, the following description will provide a snapshot comparison of both these control systems, DCS and SCADA in different sides so that the user can benefit from the control system which made:

ABB DCS PLC SCADA
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System integration and device configuration

There are two different approaches between SCADA / PLC and DSC for system integration and configuration of this device. In SCADA systems / PLC integration between HMI systems, communication controllers and some controllers and Address Control (tag) must be manually mapped in engineering documents to the entire system so that the time consuming and error prone. While in the DCS system integration and device configuration HMI and the communication system can be done automatically by the software used to manage a single database that is used by all components of the system. This allows engineers to understand the environment in a matter of a few days so the potential savings of 15-25% depending on how much HMI and worrisome being designed into the system.


Control Logic Development

In the design of PLC / SCADA control system, control engineers responsible for integration / linking multiple databases and communication systems HMI programmed independently to create a system. This approach uses data scalability, alarm levels, and location tag (address) leads to a non-standard applications. These methods have difficulty in setting redundancy so that redundancy is rarely used by the PLC.

DCS control system is able to configure the HMI face plates, alarm and communication systems that automatically using the same alarm level and scalability appropriate to the control logic. Some important data elements set only once in the system by having your calendar on the desktop and the mobile phone automatically. Users can make savings of 15-45% by arranging redundancy in software quickly and easily, almost with a click of a button.


Automatic Commissioning and start-up to simulates the application

To test whether control system can run smoothly then performed the commissioning process. In the SCADA system, system testing PLC / HMI is usually done at work after all the wiring is completed. This process requires a comprehensive effort to write programming code that will simulate your application control. Constraints faced are the high cost and complex programming, so it is rarely done.

When you use DCS system, commissioning is done automatically by simulating processes based on logic, HMI and alarms that will be used by the operator in the factory. This automated process can save significant time in place since the programming has been tested before starting the cable so that companies can get 10-20% efficiency depending on the complexity of the start-up and commissioning.


Root Cause Analysis and Troubleshooting

The data connection from the HMI to the PLC / SCADA is currently a problem in the design of this control system, for example if an input or output connected to the system, the control logic will be programmed into utilizing point control, but if there is an update system data sent via the HMI is not connected to a PLC / SCADA automatically. This will disrupt the process alarm of the points being communicated to other controllers.

Whereas if you use a DCS-based control system, all information is automatically available to the operator based on the logic that will be executed in the controller. This transfer is a model of excellence can reduce the time required to identify. In addition operators also have access to view graphical function blocks as they walked to see if the system is running normally, or there is a problem. Root Cause Analysis right one can save 10-40% of the time and cost spent to develop HMI and keep the system up to date.


Adaptable to new application requirements

One of the problems when using the design of PLC / SCADA is when there is a change of control logic to meet the needs of new applications requiring data documents additional requirements for integrating new functions into the operator station. This often happens to change the entry point to the new address, or tags, and changes must be manually propagated throughout the system.
By using the DCS control system of the change process becomes easier with the built-in and custom library code. Changes that occur automatically follow changes in the data entered into the logic of control and spread to all aspects of the system so that it can minimize errors and save 20-25%.


Authority Operator Training System

The training process based application PLC / SCADA is the responsibility of application developers not a vendor for each faceplate, HMI screen or alarm management functions can be set different from the next and this can only be understood by the application developer. While the DCS control system for operator training is available from the vendor of process control. Vendors can perform operator training because the standard of the same information presented and of course with such a system is more cost-effective operator training can usually save 10 -15 per cent of the training costs.


Documentation management

Documentation system / SCADA should be done thoroughly to keep any document up to date. However, often causes a lot of problems with the number of future changes and troubleshooting. While the DCS-based documentation system for all aspects of the system are automatically created. With a system like this can save 30-50 percent depending on the nature of the system put in place.


Conclusion

DCS assumption is the conventional systems and need large devices, expensive and very complex so it makes a lot of engineers usually opted for PLC and SCADA HMIs or for smaller applications, in order to keep costs down. However, the assumption is not appropriate at this time. Some advantages of using DCS as described above could be an alternative option for the control engineer to design control systems appropriate to their needs.


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