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9 Modbus RTU – integrated Modbus port specification
9.3 Modbus register map
68
PXR Electronic trip unit
01/21 MN012005EN
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9.3.4 Event logs
A trip event provides historical values for the data objects at time the event
occurred. The trip unit classifies the event information in order to be able to
provide a different quantity for each type. The Modbus communication can
only access the historical summary, as well as the trip and event data.
Table 29: Event classification
A single trip may be registered under multiple event types. For example, a
protective trip may be recorded in the summary log (
table 31).
Event information is accessed by selecting the event type and the event ID.
Register 408193 is a R/W register for selecting the event type and must be
written with function codes 06 or 16. The event information can be read with
function codes 03 or 04.
If the event type selection is written to register 408193, the first and last
event ID can be retrieved from registers 408194 and 408196, respectively, in
order to determine the range of events that have been stored for the
selected event type. Register 408198 is a R/W register for selecting the ID of
the event in question and must be written with function code 16. If the
requested event has been recorded by the device, registers 408200 and
408202 will supply both the ID of the previous event and that of the next
event. If the device has not recorded the event in question, it will return the
exception code 07.
The date and time at which the requested event occurred are read in logs
408204 to 408211, with the same date and time description as in
→
table 35, page 77. This value corresponds to the time at which the
historical event occurred.
Log 408212 indicates the data content of the selected event type. This is a
constant value for the three event types supported by the Modbus port.
The event data also provide a validity bit for each data object, starting with
register 408213. If bit 0 is set to 1, the initial data will be valid for the current
trip type, bit 1 for the second data object, bit 2 for the third data object, and
so forth.
The number of valid bit registers is calculated as:
(number of data objects - 1)/16
The following registers are assigned to the data objects. Any request outside
the range of the register address will return the exception code 02.
Event type
Quantity of numbers
stored
Description of the event log
Summary
200
Tripping
10
Alarms
10