18 years ago
Saw this topic on the newsgroup quite sometime ago.
Will like to share my views.
PLC are machines that perform control function via it's input and
output port. It can be a very complex system (example with SCADA, HMI
etc). But I think it is common that PLC system is relatively small
system and works independently.
DCS are large PLC system. It comes with HMI, and most likely SCADA. It
provides more inputs and outputs as compare to PLC. It is normally DCS
is a more integrated system. The word "Distributed" also indicted that
most likely the system is kinda "decentralised" system, with a lot of
CPUs working independently, but they are linked with information(data)
Sometime there is only a thin line between PLC and DCS. If a PLC
system grows too big, it might be mistaken as a DCS.
DSP is Digital Signal Processing or sometime people will call it
Signal Processing. I think Signal Processing is a better name as
Digital Signal Processing is quite restricted in some sense.
Signal Processing mainly deal with signal. Analysis of incoming signal
and processing the incoming signal. The DSP chip (embedded device) is
a device used to analysis the signal using the programming (normally
some math routines like Fast Fourier Transform, Discrete Cosine
Transform, etc) it contains. It is part of Signal Processing, but not
the main part.
Therefore, I think DCS and PLC can be consider as System, while Signal
Processing is consider as Signal.
There is also only a thin line between Signal and System. Signal can
be analysis using system method and system can be analysis using
Have a nice day.