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Sampling Rate
The frequency with which samples of a physical variable, such as sound are taken. The higher the sampling rate, the more closely the digitized result resembles the original.
Scan Time
The time to completely execute a PLC program once, including I/O update.
SCADA (Supervisory Control and Data Acquisition)
The level of applications that monitor and control devices such as programmable controllers. These systems are usually PC or workstation based.
SDS (Smart Distributed System)
An advanced bus system for intelligent sensors and actuators developed by Honeywell Inc., Micro Switch Division. The SDS specification covers physical layer and application layer. Smart Distributed System devices have advanced device-level functions, system and device diagnostics.
Sensitivity
Refers to a device's ability to discriminate between levels. If it's a sensor it would relate to the finest difference it could detect. If it were an analog module for a PLC, it would be the smallest change it could detect.
Sensor
Device used to detect change. Normally it is a digital device. The outputs of sensors change state when they detect the correct change. Sensors can be analog or digital in nature. They can also be purchased with normally closed or normally open outputs.
Serial communication
Sending of data one bit at a time. The data is represented by a coding system such as ASCII.
Servo Motor
A power-driven mechanism that supplements a primary control operated by a comparatively feeble force (as in a servo mechanism).
Slave
On a master-slave configured network, there is usually one master and several slaves. The slaves are nodes of the network that can transmit informations to the master only when they are polled (called) from it. The rest of the time a slave never transmits anything.
Speech modules
Used by a PLC to output spoken messages to operators. The sound is typically digitized human speech stored in the module's memory. The PLC requests the message number to play it.
SQL (Structured Query Language)
A standard language that can be applied to query and update data sources that support the ODBC standard.
System Integration
The process of connecting systems, devices, and programs together in a common architecture so as to share and exchange data.
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