5 Other Functions
5-2
NJ/NX-series Database Connection CPU Units User’s Manual (W527)
5-1 Examples of Using Functions
This section explains examples of using functions described in this chapter.
DB Connection Service has various functions corresponding to various events that will occur in
exchange of data with the relational database in the server.
The typical events that can occur, the outline of their countermeasures, and the relationship
between the events and DB Connection Service functions are shown below. For details on how
to deal with it, refer to the following items described in this section.
No. Typical events
Effects of the event
when it is occurred
Outline of the
countermeasures
Reference in this
section
1 When the interruption of
the power supply to the
Controller occurred
• Possibility of loss of
SQL statements to be
sent
• As a result, the
possibility of missing
data stored in the
relational database
When resending the
SQL statement the next
time the power is turned
ON, take measures on
the user program in
combination with the
Spool function Refer to 5-2 Spool
Function
Refer to 5-4 How to
Prevent Losing SQL
Statements at Power
Interruption
• Use an uninterruptible
power supply for the
power supply of the
Controller. If the power
supply using the
uninterruptible power
supply can not be
maintained, shut down
the DB Connection
DB
Connection
Service
shutdown
function
Refer to 5-3 DB
Connection Service
Shutdown Function
Possibility of loss of
Operation Log data
• Use an uninterruptible
power supply for the
power supply of the
Controller. If the power
supply using the
uninterruptible power
supply can not be
maintained, shut down
the DB Connection
DB
Connection
Service
shutdown
function
Refer to 5-3 DB
Connection Service
Shutdown Function
2 When a load in the server
temporarily increased
• Possibility of DB
Connection Service
delay
• As a result, the
possibility of missing
data stored in the
Implement the
countermeasures using
the timeout monitoring
functions.
• Timeout
monitoring
functions
• Spool
function
Refer to 5-5 Timeout
Monitoring Functions
Refer to 5-2 Spool
Function
3 When a response speed in
the server relatively
continued to decrease for
a long time
Possibility of missing
data stored in
relational database
due to insufficient
spool capacity
To prevent missing data,
implement one of the
followings until the
spooled SQL statement
is resent and the
capacity shortage is
resolved.
• Pause or slow down
operation of the
Spool function Refer to 5-2 Spool
Function
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