communication between pc and plc S7-200 through rs232

I have documents which explains the protocol ppi (explains the formats
of frame accepted by the CPU of the S7-200 automat).
I wrote a code which ensures the communication between PC and s7-200. I tested but it
does not function I have make several checking:
- I have an achievable file which ensures the communication between PC s7-200.
I used a serial monitor to know the frame exchanged between PC and
automat I noted that they similar to those are used in my code I have
doubts about times (use of structure COMMTIMEOUTS)
typedef struct _COMMTIMEOUTS { // ctmo
DWORD ReadIntervalTimeout;
DWORD ReadTotalTimeoutMultiplier;
DWORD ReadTotalTimeoutConstant;
DWORD WriteTotalTimeoutMultiplier;
DWORD WriteTotalTimeoutConstant;
} COMMTIMEOUTS,*LPCOMMTIMEOUTS;

language used is C++

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