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PT UNIT USER MANUAL
APRIL 2023 www.eaton.com.cn
A.3.4 Event Register
The triggering of an event in the trip unit can provide
historical data object values at the instant in time the event
occurs or occurring around the time of the event. The trip
unit categorizes the event information into classifications
to provide various numbers of each type. Modbus
communication can only have the access to obtain the
historical summary, trip, and alarm event data, as shown in
Table A6.
Table A6. Event Classification
Event Type
Number Stored
Event Register Description
Historical Summary
200
Table A7
Historical Trip
10
Table A8
Historical Alarm
10
Table A8 and Table A9
A single triggering can place information into multiple event
types. For example, the occurrence of an event triggered by a
circuit breaker trip may provide both historical summary (see
Table A7) and historical trip information (see Table A8).
Access to event information is based on the selection of
event type and event ID. Register 408193 is a R/W register
used to select the event type, using function code 06 or 16 to
write. The event information may be read by using function
code 03 or 04.
When the event type selection is written in register 408193,
the earliest and latest event ID can be obtained in registers
408194 and 408196 respectively to determine the range of
events saved for the selected event type. Register 408198
is a R/W register used to select the requested event ID and
is written with function code 16. If the request event exists
in the trip unit, registers 408200 and 408202 provide the
Previous Event ID and Next Event ID respectively. If the
requested event does not exist in the trip unit, exception
code 0x87 is returned.
The date and time when the requested event happened
is read in registers 408204 through 408211. This value
corresponds to the time of occurrence of the historical event.
Register 408212 stores the selected event type's data
content. This is a constant value for the three event types
that Modbus port supports.
Event data also provides a validity bit for each data object,
starting from register 408213. Bit 0 set to be 1 indicates
that the first data object is valid and bit 1 is used to indicate
the second data object is valid. The number of validity bit
registers is calculated as (number of data objects–1)/16. The
registers listed in Tables A7, A8, and A9 are the data objects.
A request out of the range of the registers address would
result in exception code 02.
Table A7. Historical Summary Event
Register
Format
R/W
History Summary Event
408193
Encoded
R/W
Event type: Alarm = 8EFF
16
408194
Unsigned 32
R
Earliest Event ID
408196
Unsigned 32
R
Latest Event ID
408198
Unsigned 32
R/W
Requested Event ID
408200
Unsigned 32
R
Previous Event ID
408202
Unsigned 32
R
Next Event ID
408204
Unsigned 32
R
Date/Time
408212
Date/Time
R
Format of Data: 0000
16
, 0001
16
,
0004
16
, 0005
16
, 0006
16
,
408213
B0
R
Object Validity Bit
408214
Encoded
R
Event Cause:
00 = Power Up - Time OK
01 = Setpoints Download
02 = Time Adjusted
03 = Trip
04 = Alarm
05 = Enter Test Mode
06 = Exit Test Mode
08 = Power Up - No Time
09 = Test Completed
10 = Inactive
11 = Inactive
12 = Opened by Communications
13 = Closed by Communications
Appendix A - Modbus Communication Port Setting
