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  2. Current loop - Wikipedia

    en.wikipedia.org/wiki/Current_loop

    A major application of current loops is the industry de facto standard 420 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 ...

  3. Highway Addressable Remote Transducer Protocol - Wikipedia

    en.wikipedia.org/wiki/Highway_Addressable_Remote...

    When sent over 420 mA it uses a Bell 202 for layer 1. But it is often converted to RS485 or RS232. According to Emerson, [2] due to the huge installation base of 420 mA systems throughout the world, the HART Protocol is one of the most popular industrial protocols today. HART protocol has made a good transition protocol for users who ...

  4. Digital current loop interface - Wikipedia

    en.wikipedia.org/wiki/Digital_current_loop_interface

    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 ...

  5. Fieldbus - Wikipedia

    en.wikipedia.org/wiki/Fieldbus

    This is because many devices share the same set of cables in a multi-dropped fashion rather than requiring a dedicated set of cables per device as in the case of 420 mA devices. Moreover, several parameters can be communicated per device in a fieldbus network whereas only one parameter can be transmitted on a 420 mA connection.

  6. Main distribution frame - Wikipedia

    en.wikipedia.org/wiki/Main_distribution_frame

    The MDF is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires at the MDF. All cable copper pairs supplying services through user telephone lines are terminated at the MDF and distributed through the MDF to equipment within the local exchange e.g. repeaters and DSLAM.

  7. Residual-current device - Wikipedia

    en.wikipedia.org/wiki/Residual-current_device

    A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device, more specifically a form of Earth-leakage circuit breaker, that interrupts an electrical circuit when the current passing through line and neutral conductors of a circuit is not equal (the term residual relating to the imbalance), therefore ...

  8. Elephants cannot sue to get out of the zoo, Colorado's top ...

    www.aol.com/news/elephants-cannot-sue-zoo...

    Five elderly African elephants at a Colorado zoo will stay there, after the state's highest court said the animals have no legal right to demand their release because they are not human. Tuesday's ...

  9. Instrumentation - Wikipedia

    en.wikipedia.org/wiki/Instrumentation

    Transistor electronics enabled wiring to replace pipes, initially with a range of 20 to 100mA at up to 90V for loop powered devices, reducing to 4 to 20mA at 12 to 24V in more modern systems. A transmitter is a device that produces an output signal, often in the form of a 420 mA electrical current signal, although many other options using ...