Instrumentation And Control (I&C) Engineering

Field instrumentation is the interface between the control system and the physical world. Field instruments are classified to SENSORS and ACTUATORS. Sensors provide information to the PLC and actuators perform actions by the PLC commands. Almost any physical value may be measured by sensors and translated into standardized electrical signals. Such a standard ensures easy integration between an instrument and any suitable control module, vendor independent. Actuators translate electrical signals into physical actions, like open or close, turn, heat, regulate etc.

There are two main principles of field data exchange: the wired connection and Fieldbus. In years, the information becomes increasingly compressed. Vendors attempt to squeeze as much as possible data into so-called “single channel”. Field instrumentation also has been affected by this trend. Some time ago, there were only hard wired connections over junction boxes to the control modules. Also, control modules could be located only on the main CPU rack. Then control systems got a possibility to be expanded to several racks using special data cables and special protocols exclusively by a vendor. It was first DCS! Now, field instruments become smart and also got their communication capabilities. So, the instrumentation level network got its name Fieldbus.

There are also standardized protocols such as ASI, Profibus PA, FF, CAN, DeviceNET and others. All of them – serial networks, usually RS-485 or RS-422. But field level doesn’t require more information capability. Apart from field instrumentation, more and more VFDs also get connected to control systems over ethernet or serial buses. Instrumentation engineering joins physical connection to the process and electrical connection to the control system. From the knowledge aspect, it is one of widest disciplines. Promacon LTD offers its services in instrumentation engineering and commissioning. We also offer supervision services where instrumentation contractor makes installation and wiring. Our specialists are completely familiar with Emerson, Yokogawa, ABB, Siemens, Rockwell and others vendors.


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