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On the master slave problem of S7-200 smart
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MBus is used in both programs_ CTRL and MBus_ MGS
The two PLCs call Modbus RTU communication;
The first program uses net_ Exe command, the second program does not.
The first PLC calls Ethernet S7 communication, which is the client of S7;
The first PLC is connected to the second PLC and an HMI via an Ethernet switch
The second server is the server of S7 communication.
Which of the three devices is the master station and which is the slave station, how to judge. Please give me some advice. You can give some examples and recommend some materials.
: if you ask about S7 communication, the first PLC is the client (you can understand the master station). The second PLC is (server). You can understand the slave station.
S7 communication summary:
S7 communication is a relatively simple form of Siemens Ethernet communication, which is mainly the client alarm of S7 communication. Besides the S7 communication program, the server does not need to edit the communication program of S7, but only needs to prepare a communication data exchange area.
In addition, the two PLCs are used as the master station of Modbus RTU communication.
S7 communication data, http://www.ad.siemens.com.cn/productportal/prods/s7-200-smart-portal/200smarttop/smartsms/016.html
Reply to supplementary questions:
This is the setup for get / put seen in the first program, as shown in the figure. Do 1 and 2 in Figure 1 refer to the second PLC?
You can understand the host computer as a hardware configuration
The remote PLC in Figure 2 refers to the second PLC? Reading data from vb1000-vb1002 refers to reading data from remote PLC? Then write to the local CPU (the first PLC)?
Yes, it refers to the server. You understand it as a slave.
Your picture is quite messy. I can't confirm your drawing number. Data length is defined. 3 bytes or 60 bytes
Get and put instructions are read and write of Ethernet.
It can only be the V storage area. If there are other addresses, you need to transfer them to the V storage area first, and then exchange the communication data.
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