Basics of program execution
7.4 Special instructions for S7-1500R/H redundant systems
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
159
To ensure high availability for the baggage handling system, you use an S7-1500R/H
redundant system as controller. If one of the CPUs fails (loss of redundancy), the
S7-1500R/H redundant system switches from the RUN-Redundant system state to RUN-
Solo. A CPU continues to ensure the control of the baggage handling system, but no second
redundant CPU is available.
Replace the failed CPU with a replacement CPU. The procedure for replacing the CPU is
described in the section Replacing defective R/H-CPUs (Page 260).
As soon as you set the exchanged CPU to RUN, the R/H-System responds as follows:
●
The replaced CPU (Backup CPU) switches to SYNCUP operating state and sends a
corresponding status message to the primary CPU.
●
The primary CPU then switches from the RUN operating state to RUN-Syncup.
●
The S7-1500R/H redundant system then does not run a SYNCUP.
During SYNCUP, the user program of the primary CPU runs through a cycle with an
extended cycle time. In this cycle, there is a delay before the redundant system responds to
input signal changes.
If a piece of baggage passes the scanner during the SYNCUP, the redundant system only
responds to the scanner after the extended cycle described above. In the worst case
scenario, the piece of baggage has already passed the deflector before the system
responds. The piece of baggage is then moved to baggage claim rather than to the
connecting flight.
Feature
You need the "RH_CTRL" instruction, which allows you to disable and enable the execution
of the SYNCUP as required.
Solution
You use the bushing of "RH_CTRL" instruction to disable the execution of the SYNCUP
system state for the S7-1500RH redundant system. If the disable is no longer required, you
enable the execution of the SYNCUP again with the "RH_CTRL" instruction.
Disable the SYNCUP bushing state to avoid a long program cycle when the baggage
handling system is operating at or near capacity. To do so, call the "RH_CTRL" instruction
with block parameter MODE = 3 in the user program.
Replace the failed CPU with a replacement CPU.
As soon as you set the exchanged CPU with disabled SYNCUP to RUN, the R/H-System
responds as follows:
●
The exchanged CPU (Backup CPU) shows the SYNCUP state.
●
The Primary CPU then displays the RUN-Syncup state.
●
The redundant system does not yet perform any SYNCUP and remains in the RUN-Solo
system state.
As soon as the baggage handling system is operating at low capacity, for example at night,
enable the SYNCUP system state. To do so, call the "RH_CTRL" instruction with block
parameter MODE = 4 in the user program.
The redundant system does not run a SYNCUP. The redundant system then switches to the
RUN-Redundant system state. Now disable SYNCUP again by calling the "RH_CTRL"
instruction in the user program with the block parameter MODE = 3.
Summary of Contents for Simatic S7-1500H
Page 1: ......
