Basics of program execution
5.3 Asynchronous instructions
CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)
52 Operating Instructions, 09/2016, A5E35873416-AA
Assignment of call to job of the instruction
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.
D_ACT_DP LADDR
CREATE_DB LOW_LIMIT, UP_LIMIT, COUNT, ATTRIB,
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