Campbell CR300 Series Product Manual page 245

SDI-12
Serial Data Interface at 1200 baud. Communication protocol for transferring data
between the data logger and SDI-12 compatible smart sensors.
SDK
Software Development Kit
SDM
Synchronous Device for Measurement. A processor-based peripheral device or sensor that
communicates with the data logger via hardwire over a short distance using a protocol
proprietary to Campbell Scientific.
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 ther-
mocouple temperature measurement. It also causes small, correctable voltage offsets in
data logger measurement circuitry.
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-inter-
rupted measurement execution of the main scan.
send button
Send button in data logger support software. Sends a CRBasic program or operating sys-
tem to a data logger.
sequential mode
A CRBasic program execution mode wherein each statement is evaluated in the order it is
listed in the program.
Appendix C. Glossary 232