Behaviour Under Special Operating Conditions - Siemens SIPROTEC4 7SJ61 Manual

2.2

Behaviour under special operating conditions

7SJ61/62/63, 6MD63, 7UM61 PROFIBUS-DP – Communication profile
C53000-L1840-B001-02
Execution of switching operations via PROFIBUS-DP
•
A change of the switching device status which was not initiated by
the PROFIBUS-DP master (e.g. circuit breaker trip) is recognized by
the PROFIBUS-DP master by a change of the value of the switching
device status in the corresponding bit positions of the input
message. If the PROFIBUS-DP master wants to reclose the locally
switched off switching device, then the current value (OFF) or
"quiescent status" must first be transmitted via PROFIBUS-DP and
then the switching device can be reclosed by setting the must-value
to ON.
•
A switching operation requested via PROFIBUS-DP which cannot be
executed (e.g. because the control authority is set to LOCAL or the
corresponding interlock conditions in the bay are not fulfilled), is
recognized by the PROFIBUS-DP master from a discrepancy
between the checkback signal of the double command or the status
of the single command in the PROFIBUS-DP input message and the
requested switching status (a checkback supervision time may be
activated in the PROFIBUS-DP master). Before starting a new
switching attempt, first the current switching status as per the input
message or "quiescent status" has to be transmitted again in the
output message via PROFIBUS-DP.
•
The response in the event of disturbed communication is described
in chap. 3.
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