Db_Read - Siemens SIMATIC S7 Operating Instructions Manual

SIEMENS AG

db_read

The function db_read reads an "amount" of data words from a data block in the
PLC and transfers them into a variable field of the PG/PC.
If the data block does not exist, this is indicated by a return value = error
number.
If the data which is being read, exceeds the amount available in the data block,
the " amount" is corrected and error message 303 hex is returned.
Important!
The data words are stored in the "buffer" not in accordance with Intel-Notation
(low byte - high byte) but in STEP5-Notation (high byte - low byte). This is
important if the data is processed further.
If there were no errors, the function supplies 0 as the return value otherwise an
error message which can be evaluated in accordance with the error table (see
error_message).
See also db_write
C-Adapter
int db_read
(int dbno, int dwno, int* amount, void* buffer);
Toolbox for Data Link PGs/PCs to SIMATIC S7
27
PRODAVE S7
(mini)