Figure 5: Time synchronisation
To ensure that all events within an installation are recorded in the correct sequence,
all Profibus DP-V2 field devices must have the same time information. For this
purpose, the master cyclically sends the current time to all field devices.
Basic procedure during communication startup
1. During communication startup, a parameter telegram is sent from the master
to the actuator. The parameter telegram contains parameters for configuring
the time stamp and time synchronisation.
2. The master then cyclically sends Time_Event and Clock_Value telegrams to
synchronise the time.
3. The actuator sends the startup data of the time stamp (current state of the sig-
nals to be stamped).
Procedure during operation:
1. The actuator detects an event, stamps the time and sends a high priority re-
sponse telegram (in the DataExchange state).
2. The master reads the alarm information from the actuator using a diagnostic
telegram.
3. The master acknowledges the alarm.
4. The master reads the indicated data record (event with time) from the actuator.
The following events are stamped by the actuator with a resolution of 10 ms
End position CLOSED
End position OPEN
Torque sw. CLOSED
Torque sw. OPEN
Selector sw. REMOTE
Fault
Phase fault
A time stamp is made for any change of state of these signals, for both rising and
falling signal flank.
47
Actuator controls
AC 01.2/ACExC 01.2 Profibus DP Description of the data interface
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