Term. DTE
Data Terminal Equipment. While the term has much wider meaning, in the
limited context of practical use with the CR1000, it denotes the pin
configuration, gender, and function of an RS-232 port. The RS-232 port on
the CR1000 is DCE. Attachment of a null-modem cable to a DCE device
effectively converts it to a DTE device. See Term. DCE
(p. 513).
Term. duplex
A serial communication protocol. Serial communications can be simplex,
half-duplex, or full-duplex.
Reading list: simplex
(p. 528), duplex (p. 248), half-duplex (p. 517), and full-duplex
(p. 516).
Term. duty cycle
The percentage of available time a feature is in an active state. For example,
if the CR1000 is programmed with 1 second scan interval, but the program
completes after only 100 millisecond, the program can be said to have a 10%
duty cycle.
Term. earth ground
A grounding rod or other suitable device that electrically ties a system or
device to the earth. Earth ground is a sink for electrical transients and
possibly damaging potentials, such as those produced by a nearby lightning
strike. Earth ground is the preferred reference potential for analog voltage
measurements. Note that most objects have a "an electrical potential" and the
potential at different places on the earth — even a few meters away — may
be different.
Term. engineering units
Units that explicitly describe phenomena, as opposed to, for example, the
CR1000 base analog-measurement unit of milliVolts.
Term. ESD
Electrostatic discharge
Term. ESS
Environmental Sensor Station
Term. excitation
Application of a precise voltage, usually to a resistive bridge circuit.
Term. execution interval
See scan interval
(p. 526).
514
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