Application of PLC 200 in Free Port Communication

　　Description: Control two plastic molding machines. Transfer data from the two machines to the host computer. The host PC uses the MSCOMM control to enable data exchange between the two PLCs, forming a small control system.

　　1. Customer Requirements:

　　The host PC can monitor data on the PLC200 at any time and set all parameters on the host PC without affecting the operator's normal operation during production.

　　2. On-site Analysis:

　　Due to the large number of parameters to be modified and frequent product changes, the host PC uses the MSCOMM control for parameter settings, adopting a switch mode between manual operation and remote setting. Parameters such as machine pressure and temperature are set remotely on the host PC. This method does not affect production. Free port communication is used.

　　3. Solution:

　　1. Plan:

　　A small control system using PLC200 is adopted for the plastic molding machines, selecting CPU 226 and configuring corresponding modules. Smartline 1000 is used for real-time on-site operation. Communication between PLCs uses free ports, and communication between the host PC and PLC200 is realized through the MSCOMM control written in VB language.

　　2. Problems encountered in the plan:

　　① Unable to set parameters of PLC200 on the PC;

　　② Data acquisition from PLC200 fluctuates significantly;

　　③ Temperature fluctuations during machine production are large and inconsistent with the site;

　　④ Machine shaking during production is obvious and affects product quality.

　　3. Analysis and solutions to the encountered problems:

　　① There was a minor program issue; the MSCOMM control part of the program was modified and corresponding address settings were made.

　　② Due to harsh site conditions, the original thermistor and thermocouple wires were replaced.

　　③ After inspection, it was confirmed that the cooling system of the old machine was faulty.

　　④ After optimizing the PLC200 program, it was found that the hydraulic machine design requires gradual control of hydraulic pressure during pressurization.

　　4. Summary:

　　For small control systems that require frequent parameter changes and diversified production, advanced languages can be used to set parameters in PLC200.

SMART1000 is based on S7 200 and S7 300

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