Campbell CR3000 Micrologger, Operator'S Manual

Page: 554 / 644

Section 11. Glossary
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program is executed for the first time at the first occurrence of the Scan()
Interval after compilation. If the Scan() Interval does not divide evenly into
24 hours, execution will start on the first even second after compilation.
Term: scan time
When time functions are run inside the Scan() / NextScan construct, time
stamps are based on when the scan was started according to the CR3000
clock. Resolution of scan time is equal to the length of the scan. See
system time
(p. 558).
Term: SDI-12
Serial Data Interface at 1200 baud. Communication protocol for transferring
data between the CR3000 and SDI-12 compatible smart sensors.
Term: SDM
Synchronous Device for Measurement. A processor-based peripheral device
or sensor that communicates with the CR3000 via hardwire over a short
distance using a protocol proprietary to Campbell Scientific.
Term: Seebeck effect
Induces microvolt level thermal electromotive forces (EMF) across junctions
of dissimilar metals in the presence of temperature gradients. This is the
principle behind thermocouple temperature measurement. It also causes
small, correctable voltage offsets in CR3000 measurement circuitry.
Term: sequential mode
A CRBasic program execution mode wherein each statement is evaluated in
the order it is listed in the program. More information is available in section
Sequential Mode
(p. 162).
See pipeline mode
(p. 549).
Term: semaphore (measurement semaphore)
In sequential mode, when the main scan executes, it locks the resources
associated with measurements. In other words, it acquires the measurement
semaphore. This is at the scan level, so all subscans within the scan
(whether they make measurements or not), will lock out measurements from
slow sequences (including the auto self-calibration). Locking measurement
resources at the scan level gives non-interrupted measurement execution of
the main scan.