SMART PLC S7-200 communication portal common knowledge to answer

1th: communication is what?

Essentially communication ports around the combination of high and low level, to achieve 0 1 codes delivered between two devices, 0 is low level, 1 is high. Now, if I have a PLC and inverter communication, then the fact is hardware and cables throughthe communications port of the inverter produces combinations of high and low level and then delivered through the hardware code that translated into 01011010, thiscompletes the PLC to inverter data transmission. The same principle, frequency converter to the PLC return data the same way.

2nd: what is full duplex and half duplex?

Full duplex: communications port when sending data while also receiving data, the same time, send and receive simultaneously.
Half-duplex: communication ports at a time, or send or receive, plainly, is at the same time, had completed only one, either received or sent.

3rd: what is the baud rate?

Porter rate also said communications plastic rate, communications rate actually worth is 1s within communications mouth sent 0 1 code or level level of number, usually minimum of units is by bit transfer, playing a analogy, if we of communications rate for 9.6kbps, that is said communications mouth each seconds sent of 9,600 a bit of data is each seconds produced 9,600 a make died level, level level of number added up is 9,600 a.

4th: concept and effect of agreement

Usually for us beginners, many people will walk into this myth, said 485 protocol agreement, 232 protocols, this is in fact completely wrong, the first thing to know, RS232, RS485, physical media is our hardware, to put it bluntly, is the hardware interfaceis essentially a hardware carrier for transmission to receive data. And we by said of agreement, actually is equipment and equipment Zhijian communications Zhijian confirmed good of data format and data content, like I and you talk, I to wants to listening to have understand, if I said of is Chinese, you also must said of is Chinese, such first they of syntax format as, if you said of is English, data format completely not as, that how can listening to of understand, addition, also to know you said of this sentence words of content is what, such has, on has has a provides good of format and content, other received to you of information Shi, Is able to recognize and automatically analyses, we can also say to shake hands before the communication, consensus!

5th: 485 communication structure

For 485 communications,, due to industrial provides, 485 for half duplex communications way, here focus stressed, we is for Yu we of industrial communications,, industrial communications provides, so, it only a main station, has multiple from station, like we now application and the wide of Modbus communications, it only support a main station, multiple from station, first this is we to make clear, we can in many support Modbus communications of frequency device and PLC equipment of description see, it only a main station address. So between them since there is only one main station, is how to transfer the dialogue? Can we remember that, in 485 communication network, main station and from the stand for dialogue, but from the stand and through the main station from the dialogue between the stations must, then main station to another station.