I/O System S900
Communication Interface for PROFIBUS DP, CI920
4. Communication via PROFIBUS DP V1
Slave address
Conventions
Up to 127 stations can be addressed via the PROFIBUS. However, only 32
stations may be run on each line without using a repeater. Since at least one
master must exist on the bus, the maximum slave address range is 126. Note
that diagnostic or configuration devices connected only temporarily to the bus
(Class_2 masters) must be taken into account as well! Address 0 must not be
used for slaves. Address 126 is reserved for commissioning slaves whose
address can be configured via the PROFIBUS. When using two
communication interfaces (redundancy), the permissible PROFIBUS address
range is limited to 1...124., since the redundant CI920 receives a PROFIBUS
address made up of the active CI920 an (with n being configurable).
Do not assign the same bus address to two stations. This will cause a crash of
cyclic data transfer on both stations!
Setting the bus address
The setting is made via three coding switches on the termination unit.
The new address will only be active upon a CI920 restart. After changing an
address always remove and plug in again the CI920, or switch off the station
for a short time.
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