Siemens S7-1200 - Data Block Control; READ_DBL and WRIT_DBL (Read;Write a Data Block in Load Memory) Instructions

Extended instructions
8.8 Data block control
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
401
8.8
Data block control
8.8.1
READ_DBL and WRIT_DBL (Read/write a data block in load memory)
instructions
Table 8- 175 READ_DBL and WRIT_DBL instructions
LAD / FBD
SCL
Description
READ_DBL(
req:=_bool_in_,
srcblk:=_variant_in_,
busy=>_bool_out_,
dstblk=>_variant_out_);
Copies DB start values or part of the
values, from load memory to a target
DB in the work memory.
The content of load memory is not
changed during the copy process.
WRIT_DBL(
req:=_bool_in_,
srcblk:=_variant_in_,
busy=>_bool_out_,
dstblk=>_variant_out_);
Copies DB current values or part of the
values from work memory to a target
DB in load memory.
The content of work memory is not
changed during the copy process.
Table 8- 176 Data types for the parameters
Parameter and type
Data type
Description
REQ
IN
BOOL
A high signal starts the operation, if BUSY = 0.
SRCBLK IN VARIANT READ_DBL: Pointer to the source data block in load memory
WRIT_DBL: Pointer to the source data block in work memory
RET_VAL
OUT
INT
Execution condition code
BUSY
OUT
BOOL
BUSY = 1 signals that the reading/writing process is not complete.
DSTBLK OUT VARIANT READ_DBL: Pointer to the destination data block in work memory
WRIT_DBL: Pointer to the destination data block in load memory