Basics of program execution
9.2 Asynchronous instructions
Automation system
System Manual, 01/2023, A5E03461182-AK
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Assigning calls of an instruction to a job
To execute an instruction over multiple calls, the CPU must be able to uniquely relate a
subsequent call to a running job of the instruction.
To relate a call to a job, the CPU uses one of the following two mechanisms, depending on
the type of the instruction:
• Using the instance data block of the instruction (for "SFB" type)
• Using job-identifying input parameters of the instruction. These input parameters must
match in each call during processing of the asynchronous instruction.
Example: A job of the "Create_DB" instruction is identified by input parameters
LOW_LIMIT, UP_LIMIT, COUNT, ATTRIB and SRCBLK.
The following table shows which input parameters you use to identify which instruction.
Table 9- 2 Identifying input parameters for asynchronous instructions
LOW_LIMIT, UP_LIMIT, COUNT, ATTRIB, SRCBLK
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