Glossary UMSITRPDS3-1
November 2005
10-2
Field Instrument – A network element that uses current variation for digital signaling or digital plus
analog signaling.
Gauge Pressure – A pressure measured against atmospheric or barometric pressure as a reference. The
units of measurement are called gauge pressure units. For example: psig = pounds per square inch gauge.
HART – Highway Addressable Remote Transducer – A communication protocol that provides
simultaneous analog and digital signaling between master and slave devices. It is supported by the HART
Communications Foundation.
HART Network – A single pair of cabled wires and the attached communicating HART elements.
Intrinsically Safe Instrument – An instrument that will not produce any spark or thermal effects under
normal or abnormal conditions that will ignite a specified gas mixture.
Keyboard or Magnetic Pushbuttons - Three pushbuttons or keys, located under a cover on the electrical
entrance portion of the transmitter enclosure and used for local configuration of the transmitter.
Leporello - The condensed transmitter user’s manual found inside the field terminals enclosure cap. A
book that unfolds in accordion fashion.
Lower Range Limit (LRL) – The lowest value of the measured variable that a transmitter or other
measurement device can be configured to measure.
Lower Range Value (LRV) – Representing the 4 mA point in the transmitter’s output, the LRV is the
lowest value of the measured value that the transmitter can be configured to measure.
MA or p
min
- Minimum operating input pressure.
Magnetic Pushbuttons - See Keyboard.
Maximum Overrange – The maximum pressure (static + differential) that can be applied safely to a
transmitter.
ME or p
max
- Maximum operating input pressure.
Measuring Cell - Sensor.
Multi-Drop Network – A HART network having from 1 to 15 field instruments that are parallel
connected on a single 2-wire cable. This network uses digital signaling only.
Network – A network includes the following items:
• Transmitter(s)
• Network element (controller, recorder, passive non-signaling element, or other device)
• Cabling interconnecting these devices
• Barriers for intrinsic safety, if installed
• Current sense resistor
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