SMART1000 is based on S7 200 and S7 300

　　Description: The main control system uses Siemens S7 300 PLC system to communicate via Modbus RTU with the on-site third-party Schneider PLC control system. The control status of this system is determined based on the data provided by the third-party Schneider PLC. Additionally, a touchscreen is added to display the current operating status of the control system, alarm information, communication status, and to modify relevant parameter settings. The Ethernet port is retained for possible future communication with an OPC server.

　　1. Customer Requirements:

　　The cost of the upper-level touchscreen is controlled within a few thousand yuan, and the lower-level control uses Siemens 300 or Schneider PLC to achieve communication with the third-party Schneider PLC and data exchange.

　　2. On-site Analysis:

　　According to the on-site situation, if Siemens S7 300 PLC is to communicate with Schneider PLC via Modbus RTU, Siemens 300 PLC must add CP 341 and Modbus RTU master authorization. If the upper-level screen control is limited to a few thousand yuan, Siemens touchscreens cannot be used, and only domestic or third-party touchscreens can be selected.

　　3. Solution:

　　1. Plan:

　　Use Siemens S7 315-2DP/PN CPU, Siemens S7 224XP CPU, EM277, and SMART1000 touchscreen to form an automation control system without using Siemens CP341 and Modbus RTU master authorization. This meets the customer's control requirements while reducing product costs.

　　2. Problems encountered:

　　How to achieve the customer's required control effect, keep the touchscreen cost within a few thousand yuan, and still realize Modbus RTU communication.

　　3. Analysis and solution of the problems encountered.

　　Use the first port of Siemens S7 224XP to communicate with the third-party Schneider PLC via Modbus RTU to exchange data. Then use the Siemens SMART 1000 touchscreen to communicate with the second port of Siemens S7 224XP CPU via PPI communication to display the upper-level interface, alarms, control, and parameter modification. Finally, use the Siemens EM277 module to communicate with the S7 315-2 DP/PN CPU via DP protocol to exchange information, achieving the effect of S7 200 CPU controlling S7 300 CPU.

　　Company: Wuhan Haichen Industrial Control Technology Co., Ltd.

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