Siemens SIMATIC ET 200AL, System Manual

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PROFINET with the redundant S7-1500R/H system
6.4 Switched S1 device
PROFINET with STEP 7
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Behavior in system state RUN-Redundant
PROFINET communication runs on the AR between the primary CPU (IO controller) and the
standard IO device. There is no AR between the backup CPU and the standard IO device.
If the primary CPU fails or is switched to STOP, the S7-1500R/H redundant system responds as
follows:
•
The AR between the primary CPU and the standard IO device is disconnected.
• The previous backup CPU becomes the new primary CPU.
• The S7-1500R/H redundant system temporarily has no access to the inputs and no control
over the outputs of the standard IO device. During this time, the configured substitute
value behavior applies to the standard IO device.
• The new primary CPU builds an AR to the standard IO device.
• As soon as the new primary CPU has set up the AR, the S7-1500R/H redundant system has
access to the inputs again and control over the outputs of the standard IO device.
Figure 6-3 Behavior of standard IO devices in case of failure of the primary CPU
Behavior in system state RUN-Solo
Only the primary CPU is an IO controller. PROFINET communication runs on the AR between
the primary CPU and the standard IO device. There is no AR between the backup CPU and the
IO device.
OB behavior for standard IO devices with primary backup switching
If the primary CPU fails or goes to STOP, the standard IO devices temporarily fail. OB 72
"Redundancy error" is called, additional OB 86 "Module rack failure" for the failed IO devices
are not called. To detect the failed IO devices, call the DeviceStates instruction in OB 72.
With the "Switched S1 device" function, the new primary CPU establishes the ARs to the
standard IO devices again. OB 86 is called for each return of an IO device.