ABB 266 MODBUS, Руководство пользователя

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Appendix G Glossary
148 | 266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB
Term Definition
LRV, lower range value the lower range value is the lowest measured value to which the transmitter is calibrated.
LSB least significant byte (lowest)
MSB most significant byte (highest)
manifold
1) a pipe or tubular with one inlet and several outlets. 2) a pipe with several inlets and one outlet. 3)
pipes, valves, and fittings where fluid from one or more sources is directed to several systems. 4) an
area where pipelines enter and exit a pumping station or tank battery and where the control valves are
located
human machine interface, HMI a software program that converts machine instructions and commands into a user interface.
MODBUS
®
refers to the MODBUS
®
protocol standard for hardware transmitter communications. The MODBUS
®
protocol is fully described in the document entitled "Gould MODBUS
®
Protocol Reference Guide"
published January, 1985 by Gould Inc., Programmable Control Division Andover, Massachusetts.
multivariable transducer, XMV
a smart multivariable transducer that is an external stand-alone transmitter measuring static pressure
(SP), differential pressure (DP) and flowing temperature (T
f
). This refers to both the transducer portion of
the transmitter and the circuitry required to supply measurements via MODBUS
®
communications to the
host device.
NEMA National Electrical Manufacturers Association
NEMA, Type 4
a standard from the National Electrical Manufacturers Association which identifies an enclosure
constructed for indoor or outdoor use to provide protection against falling dirt, rain, sleet, snow,
windblown dust, splashing water, and hose-directed water, and remain undamaged by external formation
of ice.
NEMA, Type 4X
a standard from the National Electrical Manufacturers Association which identifies an enclosure
constructed as for Type 4 but also with protection against corrosion.
nonvolatile memory
A storage medium that maintains all data, even after suffering a loss of power. Examples of nonvolatile
memory include read-only memory and flash memory.
NPT National Pipe Thread
resistive thermal detector, RTD a device that measures temperature based upon its coefficient of resistivity
RTD resistive thermal detector
serial port
a communication interface that uses one data line (one bit) to transfer data bits sequentially. The term
serial port usually is limited to hardware that is more or less compliant to the RS-232 standard, rather
than other serial interfaces like USB and Ethernet.
span
measuring span. The algebraic difference between the start of the measuring range and the end of the
measuring range. The smallest span is the smallest value that can be selected without impairing the
specified measuring accuracy.
static pressure, SP
equals PSIG or PSIA. A unit of measure can be PSIG (pressure measurement referenced to current
atmospheric conditions) or PSIA (pressure measurement referenced to a vacuum). It is defined as the
pressure exerted by a non-moving liquid or gas. In the case of a gas well, this is the natural PSI of the
gas inside of the well.
termination the placement of a connector on a cable
termination block (also board or
panel) a circuit board with screw terminals or other connector system that allows convenient connection of field
signals and power to a data acquisition or communication system.
T
f
1) absolute temperature of flowing fluid. 2) formation temperature
thermowell
a closed-end tube designed to protect temperature sensors from harsh environments, high pressure, and
flows. It can be installed into a system by pipe thread or welded flange and is usually made of corrosion-
resistant metal or ceramic material depending upon the application.
Totalflow
product line of ABB Inc. Maker and distributor of the XSeries flow computers (XFC) and remote
controllers (XRC)
traceable standards
Traceable standards or traceability refers to an unbroken record of documentation or an unbroken chain
of measurements and associated uncertainties (accuracy). To establish and maintain traceability,
manufactured devices are tested against a benchmarked source and records are kept reflecting the
results and the allowable tolerance or accuracy standards. This testing process is often called
verification, performance validation, or calibration. While some devices may be call certified, to be
traceable, it must have the authentic documentation records.
transducer
a transmitter for converting energy from one form to another, specifically the measurement of pressure
differential in natural gas gate stations, for example, converting pressure to voltage or current
transmitter
a circuit that accepts signals or data in and translates them into a form that can be sent across a medium
(transmitted), usually over a distance. The medium can be wireless or wired.