Siemens SIMATIC S7-1500 System Manual page 385
Redundant system
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- Function manual (402 pages) ,
- System manual (393 pages) ,
- Manual (188 pages)
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Commissioning
12.4 Operating and system states
Points to note
• The CPU resets the process image input.
• All outputs are disabled or respond as configured for the given module: They provide a
configured substitute value or retain the last value output and switch the controlled
process to a safe operating state.
• Before processing the start-up routine, the CPU transfers the I/O inputs to the process
image input.
• After processing the start-up routine, the CPU releases the peripheral outputs.
Note
To read the current state of inputs during STARTUP, you can access inputs via the process
image or via direct I/O access.
To initialize outputs during STARTUP, you can write values via the process image or via
direct I/O access. The values are output at the outputs during the transition to RUN.
• The CPU always starts up in warm restart mode.
– If you define data as retentive, its content is retained beyond program startup after
– The non-retentive bit memories, timers and counters are initialized.
– The non-retentive tags in data blocks are initialized.
• During STARTUP, cycle time monitoring is not yet running.
• The CPU processes the startup OBs in the order of the startup OB numbers. The CPU
processes all programmed startup OBs regardless of the selected startup type (Figure
"Setting the startup behavior").
• If a relevant event occurs, the CPU can start the following OBs in startup:
– OB 82: Diagnostics interrupt
– OB 83: Removal/insertion of modules
– OB 86: Rack error
– OB 121: Programming error (only for global error handling)
– OB 122: I/O access error (only for global error handling)
All other OBs are started by the CPU only at the transition to the operating state RUN or
system state RUN-Redundant (OB 70).
Behavior when expected and actual configurations do not match
The configuration downloaded to the CPU is the expected configuration. The actual
configuration is the actual, physical configuration of the automation system. If the expected
configuration and actual configuration differ, the hardware compatibility setting defines the
behavior of the CPU.
384
STOP or a power failure.
You can find a description of how to use global and local error handling in the STEP 7
online help.
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
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