ABB RELION REF610, Техническое справочное руководство

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To read a fault record:
1. Write a preset single register command (function 06) to HR601 using a selection
code as data value.
2. Read the selected fault record (function 04) from HR601, register count 28.
Alternatively, a fault record can be read using one command (function 23) only.
Selection code 1: the master reads the oldest unread record
Status register 3 (HR403) informs whether there are unread fault records (see
Fig. 5.1.15.1.-2). If there is one or several unread fault records, the master can read
the contents using selection code 1.
The fault record contains a sequence number which makes it possible for the master
to determine whether one or several unread fault records have been deleted due to
overflow. The master compares the sequence number to that of the previously read
fault record.
The slave keeps track of which fault record is currently the oldest unread. The
master can continue reading fault records for as long as Status register 3 indicates
that there are unread records.
*
Special case 1: If there are no unread fault records, the contents of the last read
record is returned. If the buffer is empty, however, the registers contain only
zeros. This is the only time when sequence number zero appears.
*
Special case 2: If the master tries to read the next unread fault record without
entering selection code 1 again, the contents of the last read record will be
returned.
Selection code 2: the master reads the oldest stored record
By resetting the read pointer using selection code 2, the master can read the oldest
stored fault record. After this, the master can continue reading the following records
using selection code 1, irrespective of whether they have been read before.
Resetting the read pointer does not affect the sequence number of the
fault record.
A master reset, that is, clearing of targets and memorized values and
unlatching of output contacts, clears the fault records, after which the
sequence number starts from 1 again.
Event records
Modbus events are derived from SPA events. With a few exceptions, SPA events
update binary points in the DI and the packed HR area. Simultaneously, a
corresponding Modbus event record is generated. The event record contains the
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REF610 REF610 Feeder Protection Relay
Technical Reference Manual - ANSI Version
1MRS755535