ABB REU 610 Technical Reference Manual page 65

1MRS755972
Voltage Relay
Technical Reference Manual - ANSI Version
If an Illegal data value exception response is generated
when attempting to preset multiple registers, the contents of the
register to which an illegal value has been imposed and of the
following registers is not changed. Registers which have already
been preset are not restored.
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
28.
Selection code 1: the master reads the oldest unread record
Status register 3 (HR403) informs whether there are unread fault records (see
Fig. 5.1.15.2.-2). If there is one or several unread fault records, the master can
read the contents using selection code 1.
REU 610
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