DCS/PLC input and output signal types
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Among the DCS/PLC I/O signal types are: PT100; AI; RAI; RDI/SRDO; RAO; SRAI. What does the letter \"S\" added in front of them signify? Such as SRDO; SRAI;
PT100; platinum thermistor, which can be a transmitter or an RTD AI; (analog input) RAI; RAO, RDI, SRDO; (digital output for rotation speed) SRAI; (intelligent input for speed frequency). What does the letter ‘S’ added in front of these terms represent? S refers to speed frequency
This is the first time I’ve seen “R” and “S” added before AO; I’m not sure what “R” stands for, and I’d like to learn about it as well.
These are the symbols in the instrument circuit diagram of our factory
The first time it appears, add SR and R in front; learn *learn*.
RAI: redundant AI; RAO: redundant AO
RAI: redundant AI; RAO: redundant AO refers to redundant AI, AO； It generally refers to the requirement in industries such as petrochemicals for important control loops (such as PID loops) to have redundant AI and AO cards in the system, in order to achieve safety functions.
Does S seem to mean redundant?