Campbell Scientific CR200/CR200X-series Dataloggers - Manual (Page 184)

Appendix A. Glossary
VAC
Volts Alternating Current. 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 is used as a primary power source for Campbell Scientific power
supplies. Do not connect high-level VAC directly to the CR200(X). The
CR200(X) measures varying frequencies of low-level VAC in the range of
±20 VAC.
VDC
Volts Direct Current. The CR200(X) operates with a nominal 12 VDC
power supply. It can supply nominal 12 VDC and variable excitation in the
5 VDC and 2.5 VDC range. It measures analog voltage in the 0 – 2.5 VDC
range and pulse voltage in the ±20 VDC range.
volt meter
An inexpensive and readily available device useful in troubleshooting data
acquisition system faults.
Volts
SI unit for electrical potential.
watch dog timer
An error checking system that examines the processor state, software
timers, and program related counters when the datalogger is running its
program. If the processor has bombed or is neglecting standard system
updates or if the counters are outside the limits, the watchdog timer resets
the processor and program execution. Voltage surges and transients can
cause the watchdog timer to reset the processor and program execution.
When the watchdog timer resets the processor and program execution, an
error count is incremented in the watchdogtimer entry of the status table. A
low number (1 to 10) of watchdog timer resets is of concern, but normally
indicates the user should just monitor the situation. A large number (>10) of
error accumulating over a short period of time should cause increasing
alarm since it indicates a hardware or software problem may exist. When
large numbers of watchdog timer resets occur, consult with a Campbell
Scientific applications engineer. See WatchdogErrors p. 151 for more
information.
weather tight
Describes an instrumentation enclosure impenetrable by common
environmental conditions. During extraordinary weather events, however,
seals on the enclosure may be breached.
XML
Extensible Markup Language.
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