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WLDR ReferenceBook Page 29 Thursday, April 5, 2001 3:36 PM
WindLDR™ Reference Manual
Glossary-29
grounds, thereby allowing for long (up to two (2)
miles) communication distances.
(Also, Differential)
S
Scan Time
The time necessary to completely execute the
entire programmable logic controller’s programmed instructions one time.
Schematic
A diagram of a circuit in which symbols illustrate
circuit components.
SCR
Abbr.= Silicon Controlled Rectifier. A solid state
three (3) terminal device which employs a control
signal to switch a DC voltage load. Also known as
a THYRISTOR.
Serial Operation
A type of information transfer within a programmable logic controller whereby the bits are handled
sequentially rather than simultaneously, as they are
in a parallel operation. Slower than parallel for the
equivalent clock rate. However, only one (1) channel or wire is required for serial operation.
Setpoint
The required or ideal value of a controlled variable,
usually preset in the system’s controller by the
operator.
© 2001 IDEC Corporation
Glossary