Siemens Simatic S7-1500H - Determining the Primary CPU with Rh_Getprimaryid; Asynchronous Instructions

9.4.2 Determining the primary CPU with "RH_GetPrimaryID"
You use the "RH_GetPrimaryID" instruction to read out which CPU is currently the primary
CPU. The instruction outputs the redundancy ID of the primary CPU at the Ret_Val block
parameter.
Figure 9-4"RH_GetPrimaryID" instruction
Example: Reading maintenance information from the SIMATIC memory card of the primary CPU
Proceed as follows to read specific maintenance information from the SIMATIC memory card
of the primary CPU:
1.
Get the redundancy ID of the primary CPU with "RH_GetPrimaryID".
2.
Read the maintenance information from the SIMATIC memory card of the primary CPU
with "GetSMCInfo".
–
If the CPU with redundancy ID1 is the primary CPU, enter "12" at the Mode block
parameter ("1" for redundancy ID, "2" for maintenance information).
–
If the CPU with redundancy ID2 is the primary CPU, enter "22" at the Mode block
parameter ("2" for redundancy ID, "2" for maintenance information).
Reference
You can find more information on the "RH_GetPrimaryID" instruction in the STEP7 online
help.
9.5 Asynchronous instructions
Introduction
During program execution a distinction is made between synchronous and asynchronous
instructions.
The "synchronous" and "asynchronous" properties relate to the temporal relationship between
the call and execution of the instruction.
The following applies to synchronous instructions: When the call of a synchronous instruction
is complete, execution of the instruction is also complete.
This is different in the case of asynchronous instructions: When the call of an asynchronous
instruction is complete, execution of the asynchronous instruction is not necessarily complete
yet. This means the execution of an asynchronous instruction can extend over multiple calls.
The CPU processes asynchronous instructions in parallel with the cyclic user program.
Asynchronous instructions generate jobs in the CPU for their processing.
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Basics of program execution
9.5 Asynchronous instructions
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD