sepam 20 user manual - Schneider Electric

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DE80320
Modbus communication Time-tagging of events
Architecture for "internal synchronization" via the
communication network.
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Synchronization
Sepam accommodates two synchronization modes:
b "internal via the network" synchronization mode by the broadcasting of a "time
message" frame via the communication network. Slave number 0 is used for
broadcasting
b "external" synchronization mode via a logic input.
The synchronization mode is selected at the time of commissioning via SFT2841.
Internal synchronization via the network mode
The “time message" frame is used for both time-setting and synchronization of
Sepam. In this case, it must be sent regularly at brief intervals (between 10 and
60 seconds) in order for synchronous time to be obtained.
Sepam’s internal clock is reset each time a new time frame is received, and
synchronization is maintained if the difference in synchronism is less than 100
milliseconds.
With internal synchronization via the network, accuracy is linked to the master and
its mastery of time frame transmission in the communication network.
Sepam is synchronized without delay at the end of the receipt of the frame.
Time changes are made by sending a frame to Sepam with the new date and time.
Sepam then switches into a transitional non-synchronous status.
When Sepam is in synchronous status, if no "time message” is received
for 200 seconds, the appearance of the “not synchronous” event is triggered.
PCRED301005EN - 06/2008