what's the similarities and differences between modbus,profibus, rs-232 and rs-485(SCADA)?

Answer 1

You are talking "Apples vs oranges and pears" here.

Modbus and Profibus are both protocols, ways of encoding information for messages. It is like a language for computers to speak to one-another.

RS-232 is a physical form of connections that can be used to send electrical messages. It is an older technique that is unbalanced with respect to ground (one hot wire that goes between maximum voltage and zero to represent ones and zeroes and one ground wire for its reference) to carry the voltages. It has a limit (hundred feet or so) as to how far the messages can travel before the signals get to be so small that they are overwhelmed by noise on the line.

RS-485 is another physical form of connections that can be used to send electrical messages. It is a newer technique that is balanced with respect to ground (one hot wire goes up in voltage for a signal for ones while the other goes down for the same one and then does the opposite for a zero). It can be used to send signals for a few thousand feet because of its better immunity to noise on the lines.

SCADA is a popular way of arranging networks of sensors and actuators for collecting information from remote units and sending those remote units instructions as to how to react. Typically there is a graphical operator interface where humans can review that info and make decisions. A SCADA network can be linked using a variety of protocols and physical ways of sending ones and zeroes.

Answer 2

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RE:
what's the similarities and differences between modbus,profibus, rs-232 and rs-485(SCADA)?

Answer 3

Modbus Vs Profibus

Answer 4

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