PLC communication source code
4.0
1, through the DLL communicates with PLC based on PPI Protocol. 2, the DLL file name: S7_200_PPI.dll 3, serial port connector for PC-PPI of Siemens cable or welding 4, S7-200 PLC default parameters 5, default 100 VB bytes read, or more than 50 words of VW, via the DLL function to modify, you can read more 6, in order to simplify the procedure, only offers a v operation, and practical enough 7, when VW operation, the address should be an even