Campbell CR300 Series Product Manual page 229

full-duplex
A serial communication protocol. Simultaneous bi-directional communications. Com-
munications between a serial port and a computer is typically full duplex.
G
garbage
The refuse of the data communication world. When data is sent or received incorrectly
(there are numerous reasons why this happens), a string of invalid, meaningless char-
acters (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.
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.
ground
Being or related to an electrical potential of 0 volts.
ground currents
Pulling power from the data logger wiring panel, as is done when using some com-
munication devices from other manufacturers, or a sensor that requires a lot of power,
can cause voltage potential differences between points in data logger circuitry that are
supposed to be at ground or 0 Volts. This difference in potentials can cause errors when
measuring single-ended analog voltages.
H
half-duplex
A serial communication protocol. Bi-directional, but not simultaneous, communications.
SDI-12 is a half-duplex protocol.
Appendix C. Glossary 216