Timing Of Database Update; Precautions - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

Timing of database update

Once execution of a database access instruction is completed, the target database is updated. However, during transaction,
the database is not updated each time execution of an instruction is completed. Instead, all changes during the transaction
are applied to the database at once when the DBCOMMIT(P) instruction is executed.

Precautions

This section describes precautions on using the database function.
Free space of SD memory card required for execution of database access instruction
To execute a database access instruction, the SD memory card must have at least 10MB of free space. When a database
access instruction is performed and if the SD memory card does not have enough free space, the instruction is completed
with an error.
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When the SD memory card is write-protected
Before using database access instructions, check that the write protection of the SD memory card used is disabled. If a
database access instruction is performed while the SD memory card is write protected, the instruction is completed with an
error.
When the CPU module database access function is used
The database access instructions can be executed while SM1498 (CPU module database start-up flag) is on.
When the database is being operated by another function
Before creating a database by using the DBIMPORT(P) instruction, check that the same database is not being operated by
another function.
If the DBIMPORT(P) instruction is executed specifying a name of a database in the SD memory card while the same
database is operated by another function, the DBIMPORT(P) instruction may be completed with an error and the database
operation in another function may fail. After the DBIMPORT(P) instruction is completed with an error, if the database operated
by another function cannot be operated, the database may be broken. Power off and on or reset the CPU module, and build
the database again by using the DBIMPORT(P) instruction.
Combination of the firmware version and database
For the combination of the firmware version of the programmable controller CPU that creates a database and that of the
programmable controller CPU that can operate the database, refer to the following.
Page 259 Combination of the firmware version and database
Removal of the SD memory card
Do not remove the SD memory card while connecting to a database by using the DBOPEN(P) instruction or executing a
database access instruction. Otherwise, the database access instruction is completed with an error.
13 DATABASE FUNCTION
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13.2 Database Access Instruction