Emerson DL8000 - Page 85

DL8000 Preset Instruction Manual
Revised February-2016 Glossary A-3
dB
Decibel. A unit for expressing the ratio of the magnitudes of two electric signals on a
logarithmic scale.
DCD
Data Carrier Detect modem communications signal. In addition, Discrete Control
Device – A discrete control device energizes a set of discrete outputs for a given
setpoint and matches the desired result against a set of discrete inputs (DI).
DCE
Data Communication Equipment.
Deadband
A value that is an inactive zone above the low limits and below the high limits. The
purpose of the deadband is to prevent a value (such as an alarm) from being set and
cleared continuously when the input value is oscillating around the specified limit. This
also prevents the logs or data storage location from being over-filled with data.
Device
Directory
In ROCLINK 800, the graphical display that allows navigation through the PC Comm
Ports and ROC Comm Ports set up screen.
DI
Discrete Input.
Discrete
Input or output that is non-continuous, typically representing two levels (such as on/off).
DMM
Digital multimeter.
DO
Discrete Output.
Download
The process of sending data, a file, or a program from a PC to a ROC.
DP
Differential Pressure.
DSR
Data Set Ready modem communications signal.
DTE
Data Terminal Equipment.
DTR
Data Terminal Ready modem communications signal.
Duty Cycle
Proportion of time during a cycle that a device is activated. A short duty cycle
conserves power for I/O channels, radios, and so on.
DVM
Digital voltmeter.
DVS
Dual-Variable Sensor. A device that provides static and differential pressure inputs to a
ROC.
E
EDS
Electronic Static Discharge.
EEPROM
Electrically Erasable Programmable Read-Only Memory, a form of permanent memory
on a ROC.
EFM
Electronic Flow Metering or Measurement.
EIA-232
(RS-232)
Serial Communications Protocol using three or more signal lines, intended for short
distances. Concerning RS232D and RS232C, the letters C or D refer to the physical
connector type. D specifies the RJ-11 connector where a C specifies a DB25 type
connector.
EIA-422
(RS-422)
Serial Communications Protocol using four signal lines.
EIA-485
(RS-485)
Serial Communications Protocol requiring only two signal lines. Can allow up to 32
devices to be connected together in a daisy-chained fashion.
EMF
Electro-Motive Force.
EMI
Electro-Magnetic Interference.
ESD
Electro-Static Discharge.
EU
Engineering Units. Units of measure, such as MCF/DAY.
F
FCC
Federal Communications Commission. See http://www.fcc.gov.