Siemens SIMATIC S7-400H System Manual page 343

OB 84
If the CPU was configured as V 4.5: In case of a reduced performance in the redundant link
between the two CPUs in redundant system mode, the CPU's operating system calls OB 84.
The event "Reduced performance of the redundancy link" in the configuration as V4.5
corresponds to the event "Functional error of network component" in case of a configuration
as V6.0. OB 82 is called in case of a configuration as V6.0.
You can determine the detail diagnostics by means of SFB52 or SFB54 in case of a
configuration as V6.0.
OB 82
When operating in redundant system mode, the CPU's operating system calls OB 82 if it
detects a reduced performance in the redundant link between the two CPUs.
The cause for this reduced performance can be found in the "Sync module diagnostics" tab
in HW Config -> PLC -> Module state.
If OB 82 was called, you can only determine the cause later if the data were read out with
SFB 52 or SFB 54.
Diagnostics of the synchronization module
If you have configured a CPU 41x-5H PN/DP as V6.0, you can display the following channel-
specific diagnostic data in the tab dialog module state for the selected synchronization
module:
● Overtemperature
● Fiber-optic error
● Violation of lower limit
● Violation of upper limit
● Functional error of the network component
Fiber-optic interfaces of unused modules
Fiber-optic interfaces of unused modules must be blanked off during storage to protect the
optical equipment. The plugs are in the synchronization module when shipped.
S7-400H
System Manual, 03/2012, A5E00267695-11
The synchronization module is too hot.
The sender of the electro-optical component has reached the end of its service life.
The sent or received optical performance is low or too low.
The sent or received optical performance is high or too high.
The quality of the redundancy link between the CPUs (transmission distance including
synchronization modules and fiber-optic cables) is reduced so that transmission errors
are occurring frequently.
Synchronization modules
18.1 Synchronization modules for S7–400H
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