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Appendix A

A-76

NJ/NX-series Database Connection CPU Units User’s Manual (W527)

Structured Text (ST)

 Main Variables

Name

Data type

Initial value

Comment

DB_GetConnectionStatus_instance DB_GetConnectionStatus --- Instance of DB_GetConnectionStatus

instruction

DB_ControlSpool_instance DB_ControlSpool --- Instance of DB_ControlSpool

instruction

Trigger BOOL FALSE Variable used as a trigger for

resending the Spool data

LastTrigger BOOL FALSE Variable to retain the trigger status of

the previous execution

Operating BOOL FALSE When this variable is TRUE, the

resending processing of Spool data is

executed if necessary.

OperatingStart BOOL FALSE The initialization processing is

executed when this variable is TRUE.

Resend BOOL FALSE This variable changes to TRUE when

the status of the DB Connection is

Connected.

MyStatus _sDBC_CONNECTION_STATUS --- This variable is assigned to the

ConnectionStatus output variable

from

DB_GetConnectionStatus_instance.

MyDB1 DWORD --- This variable is assigned to the

DBConnection input variable to

DB_ControlSpool_instance.

 Sample Programming

(* ------------------------------------------------------------------------------------------------------------------------------------------------------------

- Resend the SQL statements stored in the Spool memory when the status of the DB Connection is Connected.

------------------------------------------------------------------------------------------------------------------------------------------------------- *)

// Start the sequence when the Trigger variable changes to TRUE.

IF ( (Trigger=TRUE) AND (LastTrigger=FALSE) ) THEN

OperatingStart := TRUE;

Operating := TRUE;

END_IF;

LastTrigger := Trigger;

// Sequence start processing

IF (OperatingStart=TRUE) THEN

// Initialize the instruction instance.

DB_GetConnectionStatus_instance( Execute:=FALSE );

DB_ControlSpool_instance( Execute:=FALSE );

OperatingStart := FALSE;