ABB REM 610 Technical Reference Manual page 78

REM 610 REM 610
78
Motor Protection Relay
Technical Reference Manual - ANSI Version
User-defined registers
Reading of unwanted data in a data block wastes bandwidth and complicates data
interpretation. For optimum efficiency in Modbus communication, data has
therefore been organized into consecutive blocks. In addition, a set of programmable
user-defined registers (UDR) has been defined in the holding register area.
The first sixteen holding registers, that is, HR1...16, are user-defined registers. The
UDRs can be linked to any holding register, except for HR721...727, using SPA
parameters 504V1...504V16. However, one UDR cannot be linked to another, that
is, linking cannot be nested. Each parameter contains the address of the holding
register to which the UDR is linked.
If a UDR is linked to a non-existent holding register, reading from the register fails
and an Illegal address exception response is sent. Giving the link address
the value 0 disables the UDR. If the master reads from a disabled UDR, the value 0
is returned.
The UDRs are mirrored in HR385...400.
Fault records
The data recorded during a fault sequence is called a fault record (FR). The slave
stores the five latest fault records. When a sixth record is stored, the oldest record is
deleted.
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 33.
Alternatively, a fault record can be read using one command (function 17H) only.
Selection code 1: the master reads the oldest unread record
Status register 3 (HR403) informs whether there are unread fault records (see
Fig. 5.1.14.1.-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.
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