Siemens SIMATIC S7-1500 System Manual page 233

Seq. no. of Type of call
the
call
2 to (n - 1) Intermediate
call
n Last call
Use of resources
Asynchronous instructions use resources in the CPU during their execution. The resources are
limited depending on the type of CPU and instruction. The CPU can only simultaneously
process a set maximum number of asynchronous instruction jobs. The resources are available
again after a job has been processed successfully or with errors.
Example: For the RDREC instruction, an S7‑1500R/H CPU can process up to 20 jobs in parallel.
If the maximum number of simultaneous jobs for an instruction is exceeded, the following
occurs if another job is started:
• The job is not executed.
• The ERROR output parameter returns a value of 1.
• The STATUS block parameter returns the error code W#16#80C3 (lack of resources).
NOTE
Lower-level asynchronous instructions
Some asynchronous instructions use one or more lower-level asynchronous instructions for
their processing. This dependence is shown in the tables below.
Please note that each lower-level instruction typically occupies one resource in the
instruction's resource pool.
Extended instructions: maximum number of simultaneously running jobs
Table 9-7 Maximum number of simultaneous jobs for asynchronous extended instructions and lower-
level instructions used
Extended instructions
Distributed I/O
RDREC
WRREC
ASI_CTRL
PROFIenergy
PE_START_END
PE_CMD
PE_DS3_Write_ET200S
PE_WOL
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
REQ STATUS/RET_VAL
Not relev­ W#16#7002
ant
Not relev­ W#16#0000, if no errors
ant have occurred.
Error code if errors occurred. 0
1513R‑1 PN
uses RDREC, WRREC
uses RDREC, WRREC
uses RDREC, WRREC
uses RDREC, WRREC
uses RDREC, WRREC, TUSEND, TURCV, TCON, TDISCON
Basics of program execution
9.5 Asynchronous instructions
BUSY DONE
1 0
0 1
0
1515R‑2 PN 1517H-3 PN
20
20
ERROR
0
0
1
1518HF-4 PN
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