Cyclic Data Exchange; I/O Data Transmission - ABB S900 Manual

master is capable of sending new parameter telegrams. In some older master
systems, however, the system needs to be rebooted in this case, leading to an
interruption of the online-download. Modern master systems like Symphony
CMC60 from ABB provide the required functionality and are, therefore,
perfectly suited for online-parameterization.
Uninterrupted parameter download in accordance with the PROFIBUS
specifications requires that the slave is NOT working in DPV1-mode, i.e.
there is no non-cyclic communication with a Class_1 master. All systems
acting as a Class_2 master to access DPV1 communication and capable of
sending a new parameter telegram in online mode permit online-
parameterization.
Please refer to the user documentation of the PROFIBUS master for details
about how to perform online-parameterization.
Reaction in case of erroneous parameter telegrams
To comply with the PROFIBUS specification, the DataExchange state must
be left when a negative parameter telegram acknowledgement occurs.
Therefore, S900 always acknowledges the telegram with a positive response,
even if individual module parameters were identified as erroneous. The errors
are then communicated to the operator by a diagnostic message.
Modules that receive invalid new parameters retain their previous parameters.
This ensures continuous operation of all modules that are not directly affected
by the error.

Cyclic data exchange

I/O data transmission

Measuring value status
A status bit can be assigned to every measuring value, identifying it as valid
(status bit = 0) or invalid (status bit = 1). If a measuring value is "invalid", the
3BDD010422R0101
Communication Interface for PROFIBUS DP, CI920
I/O System S900
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