ABB REM 610 - Page 81

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Momentary
Master reads Master reads Master reads Master reads
Change detect
A040332
Fig. 5.1.14.1.-1 Change detection bit
If the instantaneous value of a target bit has changed two or more times since the
master last read it, the CD bit is set to one. When the CD bit has been read, it is set
to zero.
The instantaneous and the CD bit of a certain target point always occur as a pair in
the Modbus memory map.
Modbus data mapping
There are two types of monitoring data: digital targets and measurands. For
convenience and efficiency, the same data can be read from different data areas.
Measurands and other 16-bit values can be read either from the IR or HR (read-
only) area and digital target values from either the DI or coil (read-only) area. It is
also possible to read the status of the DIs as packed 16-bit registers from both the IR
and the HR area.
Consequently, all monitoring data can be read as consecutive blocks of data from
the IR or HR area.
The register and bit addresses are presented in the tables below. Some register
structures are presented in separate sections below.
The HR and IR values are unsigned 16-bit integers unless otherwise
specified.
Motor Protection Relay
Technical Reference Manual - ANSI Version
REM 610REM 610
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