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How to Read Time-tagged Event on SEPAM

SEPAM Relay 20, 40 and 80 log the status changes / events (Logic Inputs, Remote Indications and SEPAM Check-word) with timestamp. Totally, there are 64 events message for each storage queues. SEPAM 20 and 40 have 2 internal storage queues and SEPAM 80 has 4 internal storage queues (two per communication port). The following table (Table 1) shows the modbus address for retrieving the Time-tagged Event.

text Address Table 1 Address Table 2 Read/Write
Exchange Word 0040h 0070h R/W
Event 1 0041h ~ 0048h 0071h ~ 0078h RO
Event 2 0049h ~ 0050h 0079h ~ 0080h RO
Event 3 0051h ~ 0058h 0081h ~ 0088h RO
Event 4 0059h ~ 0060h 0089h ~ 0090h RO
Table 1 – Modbus Address for retrieving Time-tagged Event from SEPAM20, 40 and 80

Exchange Word consists of Event Number and Exchange Number. Exchange Number indicates the numbering of read and for master acknowledgement. It goes back to zero after reaching the maximum value (FFh). The Event Number indicates the number of significant events are truly present in the table.

Bit 0~7
Bit 8~16
Event Number (0 ~ 4d) Exchange Number (0 ~ 255d)
Table 2 – Exchanged Word Structure

Each Event comprise of 8 words. Please refer to the below table (Table 3) for the information of the data structure. The below table is to describe the data structure of the Event message and coding method.

Word Description Sepam 20 Sepam 40 Sepam 80
1 Type of Event
2 Event Address
(refer to Table 4)
3 Reserved
4 Event Direction
0: Falling edge, 1: Rising edge
5~8 Event Time
Event Time (IEC) (Refer to Table 5)

Table 3 – Structure of Time-tagged Event

To read the remaining event message, please write xx00h into modbus address 65d where xx is the current Event Number.

text Sepam 20 Sepam 40 Sepam 80
Check Word 0100h 0100h 0C8Fh
TS (Remote Indications) 0101h ~ 0104h 0101h ~ 0109h 0C90h ~ 0C9Eh
Logic Input 0105h 010Bh 0C10h ~ 0C12h
Table 4 – Event Address Range for Sepam 20, 40 and 80

Bit 0~7
Bit 8~15
Word 5 Year (00~99) 0h
Word 6 Day (0~31) Month (1~12)
Word 7 Minute (0~59) Hour (0~23)
Word 8 Millisecond (0~59999)
Table 5 – IEC Time Standard

In case one event queue is full (63 events already recorded), a “data loss” event is generated in the 64 th position and no more even can queue up.

The following is the sample for reference to retrieve the Time-tagged Event log from SEPAM 80 by using PMC Modbus software. It can be another software application which supports modbus communication.

Step 1 – First of all, please start to read the modbus addresses from 0040h (65d) to 0060h (97d). Because the Event Number is 4, there may be some event in Exchange Number 5. Thus, it is necessary to read context in Exchange Number 5.

Step 2 – Write “0500h” to modbus address 65d

Step 3 – Read the modbus address from 0040h (65d) to 0060h (97d) again. Only 3 event message is valid.

Step 4 – Please write “0500h” into modbus address 65d to clear all of the event message from the event queue to wait for the new income event.

To clear the whole event queue, please write a value “xxFFh” into the Exchange Word (65d or 112d) where xx is any exchange number to reinitialize the corresponding event queue.

Last Revised: 19 Jan 2009

Original Author: EF


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