Siemens SIMATIC ET 200M Manual page 228

Time stamping
Binary input signals are given a time stamp when they are changed. All binary
signals parameterized for this must be time stamped throughout the system with
a specified accuracy (e.g. 10 ms) when there is a change. This means that if 2
encoders of two stations on different PROFIBUS-DP master systems are being
used at the same time, the time stamps of these signal changes can only differ
by the specified accuracy (in this case 10 ms).
Time synchronization
Time synchronization ensures that all the clocks in a system have the same time.
This is achieved by a master clock in a configured cycle issuing the time to all
the other components in the automation system that have a clock. The
components use the time issued to set their own clocks.
Ungrounded
Without a conductive connection to ³ ground.
Update
You should update the interface module IM 153-2 to the latest firmware version
following (compatible) function-related expansions or performance
improvements.
Version
All products with an order number have a release number; this indicates the
version of the product. The product version is incremented with each upwardly
compatible function enhancement, production-related modification (use of new
components) or bug-fix.
Distributed I/O Device ET 200M
EWA-4NEB780600602-06
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Glossary
Glossary-11