Basics of program execution
9.2 Asynchronous instructions
Automation system
214 System Manual, 01/2023, A5E03461182-AK
Status of an asynchronous instruction
An asynchronous instruction shows its status via the block parameters STATUS/RET_VAL and
BUSY. Many asynchronous instructions also use the block parameters DONE and ERROR.
The figure below shows the two asynchronous instructions WRREC and CREATE_DB.
The input parameter REQ starts the job to execute the asynchronous instruction.
The output parameter DONE indicates that the job was completed without error.
③ The output parameter BUSY indicates whether the job is currently being executed. When BUSY
=1, a resource is allocated for the asynchronous instruction. When BUSY = 0, the resource is
The output parameter ERROR indicates that an error has occurred.
⑤ The output parameter STATUS/RET_VAL provides information on the status of the job execution.
The output parameter STATUS/RET_VAL receives the error information after the occurrence of
Figure 9-3 Block parameters of asynchronous instructions using the instructions WRREC and
CREATE_DB as examples.
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