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A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to proportional–integral–derivative (PID) controllers, supervisory control and data acquisition (SCADA) systems, and programmable logic ...
A digital current loop uses the absence of current for high (space or break), and the presence of current in the loop for low (mark). [1] This is done to ensure that on normal conditions there is always current flowing and in the event of a line being cut the flow stops indefinitely, immediately raising the alarm of the event usually as the heavy noise of the teleprinter not being synchronized ...
The HART Communication Protocol (Highway Addressable Remote Transducer) is a hybrid analog+digital industrial automation open protocol. Its most notable advantage is that it can communicate over legacy 4–20 mA analog instrumentation current loops, sharing the pair of wires used by the analog-only host systems.
A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system or SCADA (supervisory control and data acquisition) system by transmitting telemetry data to a master system, and by using messages from the master supervisory system to control connected objects. [1]
Two-wire circuits in new installations are limited to intercom and military field telephone applications, though these too are being supplanted by modern digital communication modes. To communicate in both directions in the same wire pair, conversion between four-wire and two-wire was necessary, both at the telephone and at the central office .
A digital loop carrier (DLC) is a system which uses digital transmission to extend the range of the local loop farther than would be possible using only twisted pair copper wires. A DLC digitizes and multiplexes the individual signals carried by the local loops onto a single datastream on the DLC segment.
A fieldbus is a member of a family of industrial digital communication networks [1] used for real-time distributed control. Fieldbus profiles are standardized by the International Electrotechnical Commission (IEC) as IEC 61784/61158. A complex automated industrial system is typically structured in hierarchical levels as a distributed control ...
Pertains to circuits that form parts of communications systems. Subcategories. This category has the following 4 subcategories, out of 4 total. ... Current loop; D ...