Siemens SIMATIC Ident Installation Manual page 14

Programming interface
4.1 Functions of the serial interface
Notes
● If "COM_OPEN_STD_PUF" is transferred as the buffer size, the buffer size from the
● The returned handle must be transferred as a parameter with all further calls.
● Each buffer can hold several frames at the same time. The number is restricted only by
ComRead
comInt
This function is used for the blocking receipt of frames.
Parameter
com_handle
read_data
read_number
options
Return value
≥ 0
< 0
Notes
● The call blocks if no frame is present. No timeout parameter is intended.
● This call fetches incoming frames from an internal buffer. The actual receive routine is
14
parameter assignment dialog is adopted.
the total of the lengths of all buffered frames.
(int com_handle,
ComRead
void *read_data,
int read_number,
long options)
interface handle from
Pointer to the receive buffer of the caller
Length of the receive buffer
Not used
Number of bytes read (≙ frame length)
possible error message:
•
•
•
asynchronous.
ComOpen
COM_HANDLE_FALSE
COM_2SMALL
COM_READ_ERROR
Installation Manual, 01/2013, J31069-D0131-U001-A2-7218
SIMATIC 3964R protocol for Windows 9x/XP/7