Siemens SIMATIC S7-1500 System Manual page 52

System overview
4.3 S7-1500 R/H-CPUs
Special behavior in S7-1500H when line topology is interrupted:
NOTE
Temporary disconnection of standard IO devices in case of line interruption between
primary CPU and IO device
If the line between the primary CPU and a standard IO device is interrupted, the S7-1500H
redundant system temporarily has no access to the inputs and no control over the outputs
of the standard IO device. The status of the outputs depends on the substitute value
behavior of the respective channels.
The backup CPU establishes an AR to the standard IO device. As soon as the backup CPU
has set up the AR, the S7-1500H redundant system again has access to the inputs and
control over the outputs of the standard IO device.
• Behavior in the RUN-Solo system state:
Only the primary CPU is the IO controller. 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.
In STEP 7 you configure an IO device connected via the "Switched S1 device" function by
assigning a standard IO device to both CPUs of the redundant S7‑1500R/H system.
NOTE
Standard IO devices in the redundant system S7-1500R
Standard IO devices usually do not support H-Sync forwarding.
To avoid a cycle time increase when the PROFINET ring is interrupted, integrate the standard
IO devices (without H-Sync forwarding) downstream of a switch and not in the PROFINET
ring.
NOTE
I-device as standard IO device
You cannot assign a device that you configured in STEP 7 as an I-device to the S7-1500R/H
redundant system.
In order to operate an I-device as a standard IO device on the S7-1500R/H redundant system,
always configure the I-device via GSD file.
• SIMATIC CPU as I-device
– First, configure the SIMATIC CPU in STEP 7 as an I-device with all transfer areas.
– Export the I-device as a GSD file. The GSD export can be found in the properties of the
– Install the GSD file in STEP 7.
• HMI device as I-device ("Direct key" function)
– The GSD files for SIMATIC Comfort Panel and SIMATIC Mobile Panel can be found in this
Assign the device configured via GSD file to the S7‑1500R/H redundant system.
As of FW version V2.9, you can influence the changeover time between disconnection and
return of switched S1 devices after a failure/STOP of the primary CPU. You can find more
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PROFINET interface under "Operating mode" > "I-device communication" > "Export
Generic System Description file (GSD)".
application example (https://support.industry.siemens.com/cs/ww/en/view/73502293).
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD