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I am trying to read a serial port by using api calls createfile, readfile, getcommstate, setcommstate etc...

this all requires the proper declaration of a structure "dcb"

typedef struct _DCB {
 DWORD DCBlength;
 DWORD BaudRate;
 DWORD fBinary  :1;
 DWORD fParity  :1;
 DWORD fOutxCtsFlow  :1;
 DWORD fOutxDsrFlow  :1;
 DWORD fDtrControl  :2;
 DWORD fDsrSensitivity  :1;
 DWORD fTXContinueOnXoff  :1;
 DWORD fOutX  :1;
 DWORD fInX  :1;
 DWORD fErrorChar  :1;
 DWORD fNull  :1;
 DWORD fRtsControl  :2;
 DWORD fAbortOnError  :1;
 DWORD fDummy2  :17;
 WORD  wReserved;
 WORD  XonLim;
 WORD  XoffLim;
 BYTE  ByteSize;
 BYTE  Parity;
 BYTE  StopBits;
 char  XonChar;
 char  XoffChar;
 char  ErrorChar;
 char  EofChar;
 char  EvtChar;
 WORD  wReserved1;
} DCB, *LPDCB;

My first question is how would you declare this in mapbasic? Then how to determine the structures length?

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DWORD = Integer (32-bit signed) WORD = SmallInt (16-bit signed) BYTE do not exist in mapbasic. CHAR may be done as string*1

You have to create another DLL, that sits between mapbasic and your DLL. This DLL should translate to a record format, where Mapbasic understands all the fields.

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  • thanks for your response, can you explain further about these DLL's and how this might work, thanks
    – P Thomas
    Commented Nov 15, 2011 at 21:13
  • I have assumed this _DCB structure is part of DLL function calls? Since it uses types that mapbasic do not support, you need to write a DLL, that sits as a proxy between the DLL and mapbasic. This should remap the data structure into one that mapbasic understands. That is changing BYTES to WORDS etc.
    – Uffe Kousgaard
    Commented Nov 16, 2011 at 10:07

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