Communication
USER MANUAL FPC 200 - 3/2017 83
s. If device receives no time synchronization massage for
300 s the event Time not sync is triggered.
Internal clock is written according to IEC 60870-5-4,
Binary Time 2a standard and consists of 8 characters
structure:
Table 85 Communication telegram structure of time
synchronization.
Events
3.1.5.1 Time tagging of events
For purpose of transparency of the data processed by
FPC 200, the device uses time tagging function to
timestamp specific events that occurred during its
operation. Therefore chronological order of events can
be maintained accurately. Internal time is used when
device time tags the event.
All the events that are recorded in device are available
over Modbus communication with two internal storage
queues of total 100 stored events.
3.1.5.2 Structure
The device presents up to four events at the same time
for each buffer and one control word. Structure of data
in the table looks as follows:
Control word + Event 1 + Event 2 + Event 3 + Event 4
The function of control word is to ensure correct
reception of all data, even in case of trouble and loss of
data at communication. To ensure this, it includes
number of transactions and number of events. On
device boot, number of transactions is 0.
Events are recorded in 8 word structure. Each event
consists of the following information:
- Address where the data is stored
- Exact time of the event
- Value of the event
Number of transaction: 0
… 255
Table 86 Event reading communication telegram structure.
3.1.5.3 Reading of events
Monitoring system periodically reads the control word
and checks whether there are new events available.
Only reading of control word is allowed or reading of
the whole 33 word block. For all other requests, the
device returns an error (Wrong data).
On the arrival of new events in the buffer, the device
writes the values of events into the structure in the
analogue table and increases the number of
transactions in the control word by 1 and sets the
number of written events (maximum 4).
Monitoring system reads the values of the events,
checks for any reception errors and validity of the data.
If events are present, device stops to write new events
in the buffer and waits for confirmation for those that
were sent last.
Monitoring system confirms correct reception to device
with writing into control word the same transaction
number and number of events is reset to 0.
Upon confirmation of successful reception from the
monitoring system, the device erases the transferred
events from buffer, in analog table all words for the
events are set to 0, writes new events and sets a new
control word, as previously described. Deletion of
events is only allowed if a request to read the entire
block of events has previously been issued. Namely, the
monitoring system can’t confirm events, if it did not
read them previously.
When device sends all events and clears its buffer, it
does not change the control word anymore even after
the monitoring system reads the control word.
The clock synchronization sending
telegram interval should be more than 30
sec apart.
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