Campbell CR3000 Micrologger, Operator'S Manual

Page: 561 / 644

Section 11. Glossary
561
Term: variable
A packet of SRAM given an alphanumeric name. Variables reside in
variable memory.
Term: variable memory
That portion of SRAM reserved for storing variables. Variable memory can
be, and regularly is, overwritten with new values or strings as directed by the
CRBasic program. When variables are declared As Public, the memory can
be visually monitored.
Term: Vac
Volts alternating current. Also VAC. Two definitions:
o
Mains or grid power is high-level Vac, usually 110 Vac or 220 Vac
at a fixed frequency of 50 Hz or 60 Hz. High-level Vac can be the
primary power source for Campbell Scientific power supplies. Do
not connect high-level Vac directly to the CR3000.
o The CR3000 measures varying frequencies of low-level Vac in the
range of ±20 Vac. For example, some anemometers output a low-
level Vac signal.
Term: Vdc
Volts direct current. Also VDC. Two definitions:
o
The CR3000 operates with a nominal 12 Vdc. The CR3000 can
supply nominal 12 Vdc, regulated 5 Vdc, regulated 3.3 Vdc, and
variable excitation in the ±2.5 Vdc range.
o
The CR3000 measures analog voltage in the ±5.0 Vdc range and
pulse voltage in the ±20 Vdc range.
Term: volt meter
See multi-meter
(p. 546).
Term: voltage divider
A circuit of resistors that ratiometrically divides voltage. For example, a
simple two-resistor voltage divider can be used to divide a voltage in half. So,
when fed through the voltage divider, 1 mV becomes 500 µV, 10 mV
becomes 5 mV, and so forth. Resistive-bridge
(p. 72)
circuits are voltage
dividers.