Siemens CPU 412-5H Equipment Manual page 14

Description of the device
4.2 Synchronization modules for S7–400H
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.
NOTICE
Reduced optical performance due to soiling
Even small amounts of dirt in a fiber-optic interface adversely affect the quality of the signal
transmission. This can lead to synchronization losses during operation. Protect the fiber-optic
interfaces against dirt during storage and installation of the synchronization modules.
14
Synchronization modules for S7-400H
Equipment Manual, 04/2020, A5E50072434-AA