Basics of program execution
9
9.1 Programming the S7-1500R/H
User program for the S7‑1500R/H redundant system
For the design and programming of the user program, the same rules apply for the redundant
S7‑1500R/H system as for the S7‑1500 automation system.
The user program is stored identically in both CPUs in redundant operation. Both CPUs
process the user program event-synchronously.
From the point of view of user program execution, the S7‑1500R/H redundant system
behaves like the S7‑1500 automation system. Synchronization is integrated into the
operating system and runs automatically and hidden between the primary and backup CPU.
Specific instructions and blocks for the S7-1500R/H redundant system
Specific instructions and OBs are available for the S7-1500R/H redundant system.
"RH_CTRL" instruction
With the "RH_CTRL" instruction, you can influence the redundant system as follows:
•
Lock performance of SYNCUP (Mode 3) or release performance of SYNCUP again (Mode
4).
The goal is to allow SYNCUP only in less critical process phases if necessary (see section
Disabling/enabling SYNCUP with the RH_CTRL instruction (Page 226) for more
information).
As of firmware version V2.9:
•
Request SYNCUP (Mode 7).
With this function, you can request a SYNCUP via the user program in RUN-Solo system
state.
•
Switch primary CPU to STOP mode (Mode 8, only in RUN-Redundant system state).
In an emergency (e.g. fire alarm in the area of the primary CPU), you can perform a
primary-backup switchover as a precaution with this function.
•
Switch backup CPU to STOP mode (Mode 9).
As of firmware version V3.0:
•
Query current status, whether SYNCUP is blocked or enabled (mode 10).
"RH_GetPrimaryID" instruction
You use the instruction "RH_GetPrimaryID" in the user program to read out which CPU is
currently the primary CPU (see section Determining the primary CPU with "RH_GetPrimaryID"
(Page 228) for additional information).
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S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
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