Duplicate Address Detection - Siemens SIMATIC ET 200SP Manual

Alarms, faults and system events

8.6 Duplicate address detection

8.6 Duplicate address detection
To ensure that the AS-Interface system functions correctly, all the AS-i slaves must have a
unique AS-i address on the bus.
If the same AS-i address is assigned to one or more slaves, this incorrect assignment is
referred to herein as a duplicate address.
Note
For slaves without cyclic data communication, the duplicate address detection function of the
CM AS-i master ST cannot be executed.
Duplicate addresses where slave types are different and where the states at the inputs are different.
As part of standard operation, the AS-i master monitors the data exchange for errors and
thus often excludes slaves with a duplicate address automatically from the cyclic data
exchange. This is the case for duplicate addresses in which the slave types are different
(profile identification IO code, ID code, ID2 code, and ID1 code) and duplicate addresses for
slaves having a different status at their inputs.
In "protected operation", this fault condition is displayed on the AS-i master as a
configuration error with the relevant AS-i address and the affected slaves detect a
communication error.
Duplicate addresses where the slave types are identical and where the states at the inputs are
identical or there are no inputs.
The duplicate address detection function of the CM AS-i Master ST also detects cases of
slaves with duplicate address in which the cyclic data exchange is not excluded by standard
mechanisms. Such cases include duplicate addresses in which the slave types are identical
(profile identification, IO code, ID code, ID2 code, and ID1 code) and in which the slaves
either have the same status at their inputs or have no inputs (output slaves).
When a duplicate address is detected, the AS-i master signals a duplicate address error and
automatically resets the output data of the address concerned to "0" so that the outputs of
the affected slaves are switched off. Communication with the affected slaves is not
interrupted, i.e. the slaves do not signal a communication error.
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AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004