TotalFlow XRC6490, Руководство пользователя

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B-15
TERM DEFINITION
Dew Point The temperature at any given pressure at which liquid initially condenses from
a gas or vapor. It is specifically applied to the temperature at which water
vapor starts to condense from a gas mixture (water dew point) or at which
hydrocarbons start to condense (hydrocarbon dew point).
Dewar A glass or metal container made like a vacuum bottle that is used especially for
storing liquefied gases. Also called “Dewar flask”.
DG Display Group. When display group files are created
Diaphragm A bellows inside a displacement type gas meter. Also, a membrane separating
two different pressure areas within a control valve or regulator.
Differential For an on/off controller, it refers to the temperature difference between the
temperature at which the controller turns heat off and the temperature at which
the heat is turned back on. It is expressed in degrees.
Differential Input A signal-input circuit where SIG LO and SIG HI are electrically floating with
respect to ANALOG GND (METER GND, which is normally tied to DIG GND).
This allows the measurement of the voltage difference between two signals tied
to the same ground and provides superior common-mode noise rejection.
Differential Pressure The pressure difference between two points in a system. For example, the
difference in pressure between the upstream and downstream taps of an orifice
plate, used to measure volume passing through the orifice.
Digit
A measure of the display span of a panel meter. By convention, a full digit can
assume any value from 0 through 9, a 1/2-digit will display a 1 and overload at
2, a 3/4-digit will display digits up to 3 and overload at 4, etc. For example, a
meter with a display span of ±3999 counts is said to be a 3-3/4 digit meter.
Digital A signal which has distinct states, either on or off (0 or 1). Digital computers
process data as binary information having either true of false states.
Digital Controller Assembly The Digital Controller Assembly contains the Digital Electronic Board, Mounting
Assembly and optionally a VGA Display.
The Digital Controller board provides control parameters to the Analytical
Processor board, stores and processes the data sent from the Analytical
Processor board. The Digital Controller also processes communication with
other devices.
Digital Data Information transmitted in a coded form (from a computer), represented by
discrete signal elements.
Digital Data Exchange or
Dynamic Data Exchange A Microsoft data exchange format generally used to transfer data from one
program to another. It is a very simple format to use and Totalflow customers
often use TDS to acquire data from Totalflow devices and then transfer the data
to an Excel spreadsheet using DDE. The Totalflow Driver, TDS32, supports
DDE and its network version, NetDDE.
Digital Electronics The branch of electronics dealing with information in binary form.
Digital Input Refers to the signal received in binary format.
Digital Output Refers to the signal emitted in binary format. An output signal which represents
the size of an input in the form of a series of discrete quantities.
Digital to Analog
Conversion The process of translating discrete data into a continuously varying signal.
Common uses are to present the output of a digital computer as a graphic
display or as a test stimulus.
Digital-to-Analog Converter An electronic device, often an integrated circuit, that converts a digital number
into a corresponding analog voltage or current.
DIN Deutsches Institut für Normung. German Institute for Standardization set of
standards recognized throughout the world.
DIN Rail
Rail on which modules are mounted. Allows modules to snap on and slide right
and left.
Diode A semiconductor that allows current to flow in one direction only.