Precautions for Correct Use
Execution of this instruction is continued until processing is completed even if the value of Execute changes to
FALSE or the execution time exceeds the task period. The value of Done changes to TRUE when processing
is completed. Use this to confirm normal completion of processing.
Refer to Using this Section of the NJ/NX-series Instructions Reference Manual (Cat. No. W502) for a timing
chart for Execute, Done, Busy, and Error.
This instruction cannot be used on an event task. A compiling error will occur.
This instruction can be used only for the built-in EtherNet/IP port of an NJ/NX-series CPU Unit. It is impossible
to connect to a DB via an EtherNet/IP Unit connected to an NJ/NX-series CPU Unit.
The DB Connection created by this instruction is closed in the following cases.
When a DB_Close or DB_Shutdown instruction is executed.
When the operating mode of the Controller is changed from RUN mode to PROGRAM mode.
When the DB Connection Service is stopped.
The number of DB Connections that can be established at the same time is up to three for NX701-@@20 and
NJ501-@@20 and only one for NJ101-@@20.
When the DB Connection Service was started in Test Mode, this instruction is completed normally without
connecting to the DB actually.
When a same-name DB Connection is already established, the already-established DB Connection is output to
the DBConnection output variable.
An error occurs for this instruction in the following cases. Error will be TRUE.
When the instruction was executed when the DB Connection Service was not running
When the instruction was executed while the initialization processing of the DB Connection Service
was in progress
When the instruction was executed while the DB Connection Service was stopped due to an error
When the instruction was executed after the DB Connection Service was shut down or while the DB
Connection Service was being shut down
When the DB Connection name specified in the DBConnectionName input variable is not set in any
DB Connection Settings
When the DBConnectionName input variable is a text string consisting of NULL characters (16#00)
only
When a space character is included in the text string specified for the DBConnectionName input
variable
When the DBConnectionName input variable does not end in NULL
When the connection could not be established because the address set in the DB Connection
Settings was wrong
When the DB set in the DB Connection Settings rejected the connection
When the DB Connection Service cannot communicate with the DB due to a network failure or other
causes
When the instruction was executed for the same connection at the same time
When a same-name DB Connection is already established
When the maximum number of connections that can be established at the same time is exceeded
When more than 32 DB Connection Instructions were executed at the same time
Sample Programming
Refer to the sample programming that is provided for the DB_Update instruction.
To Next Page
Loading...
