Event Description

Event = VarID + Value + Timestamp

  • VarID: It is internally managed by the system.

    VarID is unique for 1 PLC.

    User only manages the variable name.

  • Value: Event discrete value.

  • Timestamp: Time stamp in OPC DA format.

Event Data Format

Event data format is provided for information even if this structure is not accessed in system time stamping mode.

Each event time stamp entry is a 12 bytes block organized as follows:

Reserved (set to 0)

Byte 0

Value

Byte 1

Event ID

Bit 7...0

Byte 2

Bit 15...8

Byte 3

DateAndTime

SecondSinceEpoch

Bit 7...0

Byte 4

Bit 15...8

Byte 5

Bit 23...16

Byte 6

Bit 31...24

Byte 7

FractionOfSecond

Bit 7...0

Byte 8

Bit 15...8

Byte 9

Bit 23...16

Byte 10

TimeQuality

Byte 11

Each parameter is detailed hereunder.

Value Parameter

Bit 0 defines the value of the variable after change detection:

  • 0: Falling edge

  • 1: Rising edge

Event ID Parameter

The variable management assigns a unique value to each time stamped event (including SOE_UNCERTAIN event).

DateAndTime Parameter

Defines the date and time of the variable change detection.

The following table describes the DataAndTime parameter format:

Attribute Name

Type

Description/Value

Position

SecondSinceEpoch

INT32U

Number of seconds since midnight (00:00:00) 1970/01/01 (UTC time).

(0...MAX)

FractionOfSecond

INT24U

FRACT_SEC_0 (LSByte)

B7-B0
   

FRACT_SEC_1

B15-B8
   

FRACT_SEC_2 (MSByte)

B23-B16 (B23 = 1 for 1/2 s)

The time format is defined according to IEC 61850-7-2 Edition 2.

Representation of the FractionOfSecond parameter structure:

FRACT_SEC_2 (MSByte)

FRACT_SEC_1 (2nd byte)

FRACT_SEC_0 (LSByte)

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

TimeQuality Parameter

The following table describes the TimeQuality parameter format:

Attribute Name

Type

Description/Value

LeapsSecondsKnown

BOOLEAN (B7)

This bit is set to FALSE.

ClockFailure

BOOLEAN (B6)

Same meaning as I% (implicit variable) CLOCK_FAILURE.

ClockNotSynchronized

BOOLEAN (B5)

Same meaning as the I% (implicit variable) CLOCK_NOT_SYNC.

TimeAccuracy

CODED ENUM (B4...B0)

Number of significant bits in the FractionOfSecond.

Minimum time interval is: 2* –n.

In IEC norm, the TimeAccuracy represents the number of significant bits N in the FractionOfSecond.

  • For the 1 ms time stamp resolution of BMXERT module, TimeAccuracy is set to 0xx01010 bin.

  • If ClockNotSynchronized = 1, or if ClockFailure = 1 the TimeAccuracy keeps its usual value (as if the clock is synchronized).

TimeAccuracy is also used to set specific values of TimeQuality as described in the following table:

TimeAccuracy Specific Values

Values

Comments

Unspecified

0xx11111

Used in case of time stamping detection cycle not periodic.

Invalid

0xx11110

Time invalid, used in case of buffer full.

IOChannelError

0xx11101

Used in case of I/O channel error detection.

TSInit

0xx11100

Used in case of synchronization of the values with the client (done by storing a virtual event with 16-ch discrete values inside the buffer).

ClockInSync

0xx11011

Used in case of external clock during synchronization (catch up mode).

If several specific values are simultaneously detected, the precedence of TimeAccuracy specific values is:

  1. TimeAccuracy = IOChannelError (highest priority)

  2. TimeAccuracy = Invalid or TSInit

  3. TimeAccuracy = ClockInSync

  4. TimeAccuracy = Unspecified