Section 11. Glossary
Term: ground currents
Pulling power from the CR800 wiring panel, as is done when using some
comms devices from other manufacturers, or a sensor that requires a lot of
power, can cause voltage potential differences between points in CR800
circuitry that are supposed to be at ground or 0 Volts. This difference in
potentials can cause errors when measuring single-ended analog voltages.
Term: half-duplex
A serial communication protocol. Bi-directional, but not simultaneous,
communications. SDI-12 is a half-duplex protocol.
Reading list: simplex
(p. 515), duplex (p. 282), half duplex (p. 501), and full duplex (p.
500).
Term: handshake, handshaking
The exchange of predetermined information between two devices to assure
each that it is connected to the other. When not used as a clock line, the
CLK/HS (pin 7) line in the datalogger CS I/O port is primarily used to detect
the presence or absence of peripherals.
Term: hello exchange
The process of verifying a node as a neighbor. See section PakBus —
Overview
(p. 77).
Term: hertz (Hz)
SI unit of frequency. Cycles or pulses per second.
Term: HTML
Hypertext Markup Language. Programming language used for the creation
of web pages.
Term: HTTP
Hypertext Transfer Protocol. A TCP/IP application protocol.
Term: IEEE4
Four-byte, floating-point data type. IEEE Standard 754. Same format as
Float.
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