Siemens SIMATIC ET 200S Manual page 73

• The transmission rate of the PROFIBUS-DP is at least 1.5 Mbps (shorter
equidistance times can be achieved with higher transmission rates).
• The maximum equidistance is 32 ms.
• The equidistance master (class 1) must be a class 1 DP master. In other words,
a programming device (PG)/PC cannot be an equidistance master.
• In equidistant operation, only one DP master (class 1) can be active in the
PROFIBUS-DP bus system. PGs or PCs (class 2) can also be connected.
• Clocking can only be activated on the ET 200S if the equidistant bus cycle has
been activated on the DP master system and at least one electronic module
with synchronization support has been configured.
• No clocking (equidistance) is possible with the ET 200S during removal or
insertion of electronic modules.
• In equidistant operation, the ET 200S requires a starting time of approx. 150 DP
cycles to ensure clocking right through to the terminals.
Optimizing the equidistant time
• The longest delays for the digital input/output modules (parameterizable in the
case of inputs) are decisive in determining the length of the equidistant DP
cycle. Tip: Make sure during clocking that all the digital modules in the ET 200S
station have the same input delay.
• The shorter the input delays you set for the HIGH FEATURE digital input
modules, the shorter the equidistance times that can be achieved. Tip: If
possible, set an input delay of 0.1 ms for the HIGH FEATURE digital input
modules.
• The processing time of the modules should be taken into account in the case of
modules that support clocking.
• The minimum equidistance time depends on the number of modules in the
ET 200S. Tip: If possible, use 4-channel HIGH FEATURE digital input modules
to reduce the number of modules.
You can also achieve shorter equidistance times if you distribute the modules of
an ET 200S (with a large number of modules) between two ET 200S stations.
• The equidistance time is reduced if you increase the transmission rate.
Tip: Set the fastest transmission rate possible.
ET 200S Distributed I/O System
EWA-4NEB780602402-09
Configuration Options
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