Siemens Simatic S7-1500H - Page 32

Synchronization of primary and backup CPU ensures rapid switchover between CPUs in the
event of a failure of the primary CPU. If the primary CPU fails, the backup CPU takes over
control of the process as the new primary CPU.
The synchronization of the H-CPUs does not affect the bandwidth on the PROFINET.
Reference
Additional information and configuration variants (e.g. combined topology) of the S7-1500H
redundant system can be found in the section Specific configuration variants of the S7-1500H
redundant system (Page 80).
Differences between S7-1500R and S7-1500H
Table 4-1S7-1500R and S7-1500H system differences
S7-1500R S7-1500H
CPU 1513R‑1PN
CPU 1515R‑2PN
CPU 1517H‑3PN
CPU 1518HF-4 PN
Performance • Transfer rate of 100Mbps (for synchronization
and communication)
• Data work-memory:
– CPU 1513R-1 PN: max. 2.5MB
– CPU 1515R-2 PN: max. 4.5MB
• Code work-memory:
– CPU 1513R-1 PN: max. 600KB
– CPU 1515R-2 PN: max. 1MB
• Significantly greater performance than
S7‑1500R due to:
– Separate redundancy connections over
fiber-optic cable
– High computing power
• transfer rate of 1Gbps (for synchronization)
• Data work-memory:
– CPU 1517H-3 PN: max. 8MB
– CPU 1518HF-4 PN: max. 60MB
• Code work-memory:
– CPU 1517H-3 PN: max. 2MB
– CPU 1518HF-4 PN: max. 9MB
Hardware • The CPUs are identical in design with the
respective S7‑1500 standard versions.
• Synchronization of the CPUs takes place over
the PROFINET ring.
• When you use PROFINET devices with more
than two ports (e.g. switch) in the PROFINET
ring of an R-system, then H-Sync Forwarding is
mandatory for these devices.
• H-Syncforwarding is recommended for all
devices in the PROFINET ring if you are using
PROFINET devices with only 2 ports in the
PROFINET ring of an R-system.
• Part of the bandwidth on the PROFINET cable is
required for synchronization of the CPUs. Less
bandwidth is therefore available for
PROFINETIO communication.
• The CPUs each have 2 optical interfaces.
• The synchronization of the CPUs works inde
pendently from the PROFINET network via
optical fiber.
• The full bandwidth of the PROFINET cable is
available for PROFINET IO communication.
Range • Distance between the two R-CPUs:
– Max. 100m without media converter
– Several kilometers with media converter
(depends on the media converter used)
• Distance between the two H-CPUs:
– Maximum of 40km (depends on the syn
chronization modules used)
32
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
System overview
4.1 What is the S7-1500R/H redundant system?