Siemens SIMATIC S7-1500 System Manual page 103

System overview
5.3 S7-1500 R/H-CPUs
Switched S1 device
As of FW version V2.8, the S7-1500R/H redundant system supports the "Switched S1 device"
function.
The "Switched S1 device" function of the CPU enables operation of standard IO devices on the
S7-1500R/H redundant system.
Standard IO devices are always assigned to both CPUs of the S7-1500R/H redundant system.
In contrast to an IO device with system redundancy S2, a standard IO device supports only
one AR.
As of FW version V3.0, the backup CPU of S7-1500H can establish an AR to an S1 device in a
line topology. The primary CPU then receives data via the backup CPU.
• Behavior in the RUN-Redundant system state:
The PROFINET communication runs on the AR between one of the CPUs (IO controller) and
the standard IO device.
If this is the primary CPU and it fails, the redundant S7-1500R/H system behaves 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
– 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
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.
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control over the outputs of the standard IO device. The status of the outputs depends
on the substitute value behavior of the respective channels.
has access to the inputs again and control over the outputs of the standard IO device.
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF