ABB REM 610 Technical Reference Manual page 72

REM 610
72
Motor Protection Relay
Technical Reference Manual
Digital Inputs
As the master may not detect the changes of state of all digital signals when
scanning, an additional change detect (CD) target bit will be created for every
momentary target point; see the example below.
Fig. 4.1.14.2.-1 Change detection bit
If the momentary value of an target bit has changed two or more times since the
master last read it, the CD bit will be set to one. When the CD bit has been read, it
will be set to zero.
The momentary 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 table 4.1.14.2-5. Some register
structures are presented in separate sections below.
Note!
The HR and IR values are unsigned 16-bit integers unless otherwise specified.
Table 4.1.14.2-5 Mapping of Modbus data
Description
User-defined registers
UDR 1
UDR 2
UDR 3
HR/IR DI/Coil
Write-
address bit
able
(.bit) address
1 or 385
2 or 386
3 or 387
1MRS 755537
Value
Comment
range