Campbell CR3000 Micrologger, Руководство оператора

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Section 11. Glossary
541
Term: garbage
The refuse of the data communication world. When data are sent or received
incorrectly (there are numerous reasons why this happens), a string of invalid,
meaningless characters (garbage) often results. Two common causes are: 1) a
baud-rate mismatch and 2) synchronous data being sent to an asynchronous
device and vice versa.
Term: global variable
A variable available for use throughout a CRBasic program. The term is
usually used in connection with subroutines, differentiating global variables
(those declared using Public or Dim) from local variables, which are
declared in the Sub() and Function() instructions.
Term: ground
Being or related to an electrical potential of 0 volts.
Term: ground currents
Pulling power from the CR3000 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 CR3000
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. 555),
duplex
(p. 307),
half duplex
(p. 541),
and full duplex
(p.
540).
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. 82).