S

Words starting with S.

• scanOne full pass of the PLC through its program: it reads the inputs, runs the logic from the top down, then updates the outputs. Then it starts again at once.
• scan timeHow long one scan takes, usually a few milliseconds. The PLC checks every rung once per scan, so a shorter scan time reacts sooner to a change.
• seal-inA rung where the output's own contact holds the rung true after the Start button is released, until a Stop breaks it.
• sequenceA machine that moves through steps in order, one step active at a time, each step moving on when its condition is met.
• seriesContacts one after another on the same path. Every one must be true for power to flow, so it works like AND.
• SFCSequential Function Chart: a PLC language of steps and transitions, for a machine that works through its states in a set order.
• SQLThe language databases use to read and change rows in tables. A SQL Database Link runs queries the Connection Service has approved.
• stepOne state of a Sequential Function Chart. While a step is active its actions run, and its status tag is on until a transition moves on.
• stringA data type that holds text, such as a part name or a message.
• String LengthCounts the characters in a string and writes the count into a whole-number tag. The text -7 has two characters; an empty string has none.
• Structured TextA PLC language written as text, with assignments, IF and CASE choices and loops. Its statements run in order, top to bottom, every scan.
• SUBSubtracts the second value from the first and writes the result into a destination tag.