Parameters and properties
39
SIPROTEC PROFIBUS-DP - Communication profile
C53000-L1840-B001-03
2.5.1 Properties of the event list
The PROFIBUS-DP communication module has an event list with entries of the type
"Message block" (ref. to chap 3.9).
The size of the event list is set with the parameter Number of entries on the
event list (ref. to chap. 2.1.3).
Characteristic • The event list is a ring buffer.
• In the case of buffer overflow, the oldest entry is replaced by the current entry.
The PROFIBUS-DP master is informed about the buffer overflow with a bit in the
handshake byte "Control_l" (ref. to Figure 2-3).
• Only events of the type single-point indication and double-point indication are
accepted in the event list.
• Only those annunciations of the SIPROTEC device, that are in the “Cyclical
range” (ref. to Figure 2-2, "Range 1") of the PROFIBUS-DP telegram in input
direction are entered in the event list following a change.
• Changes of the value of an object (ON/COMING and OFF/GOING as well as Inter-
mediate position of double-point indications) are stored with a time stamp in the
event list.
• Entries in the event list are not made for:
− status changes,
− command sequence states (CO+/CO-, FB+/FB- or similar).
• Following initial or reboot of the device, the event list is empty.
Annunciations that were not retrieved are lost during initial or reboot of the device.
• In the event of failure of the communication, the event list is not erased.
Entries are still saved following alarm state changes and can be transmitted to the
PROFIBUS-DP master once the communication link is re-established (buffer over-
flow is indicated if necessary).
• The entries in the event list are transmitted to the PROFIBUS-DP master in the
message blocks of the PROFIBUS-DP telegram (ref. to Figure 2-2) and must be
acknowledged by the master (ref. to chap. 2.5.3).
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