Commissioning
9.4 Operating and system states
S7-1500R/H redundant system
200
System Manual, 10/2018, A5E41814787-AA
The table below gives an overview of how the redundant system starts up as well as the
various operating and system states that it goes through in the process. The following initial
situation and steps are an example.
The operating and system states are described in detail in the following sections.
Table 9- 2
Redundant system startup
No. in
diagram
Primary CPU
System state
Backup CPU
Initial situation: Both CPUs are in STOP operating state. The mode selectors are also in the STOP position.
Step 1: Switch the mode selector of the CPU that is to be primary CPU from STOP to RUN.
①
The CPU switches to STARTUP
and processes startup OB 100
and any other startup OBs.
STOP → STARTUP
The CPU remains in STOP.
②
Following successful STARTUP,
the CPU switches to RUN.
The CPU runs like a standard
CPU in RUN and processes the
user program.
STARTUP → RUN
-Solo
The CPU remains in STOP.
Step 2: Switch the mode selector on the backup CPU from STOP to RUN.
③
RUN → RUN
-Syncup
RUN-
Solo → SYNCUP
STOP → SYNCUP
The two user programs are synchronized for redundant mode. The primary CPU copies the contents of the
load and work memory to the backup CPU. The backup CPU catches up with user program processing on
the primary CPU. After successful synchronization, the memory content is identical on the two CPUs.
④
RUN-
Syncup → RUN
-Redundant
SYNCUP → RUN
-Redundant
SYNCUP → RUN
-Redundant
After SYNCUP, both CPUs switch to the RUN-Redundant operating state. Both CPUs process the user pro-
gram synchronously.
9.4.2
STARTUP operating state
Startup processing (in the primary CPU only)
STARTUP is only executed by the primary CPU.
In STARTUP, the primary CPU behaves just like an S7-1500 standard CPU.
Response
Before the CPU starts to execute the cyclic user program, a startup program is executed.
In STARTUP, the CPU compares the actual I/O configuration with the hardware
configuration that you created with STEP 7.
By programming startup OBs accordingly, you can specify initialization tags for your cyclic
program in the startup program. You can program one or more startup OBs, or none at all.
Summary of Contents for Simatic S7-1500H
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