9 Modbus RTU – integrated Modbus port specification
9.3 Modbus register map
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PXR Electronic trip unit
01/21 MN012005EN
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9.3.6 Configuration register
The non-volatile register 402001/425345 (0x07D0/0x6300) is used to
configure the release to respond to a group of data objects, some of which
are invalid for this particular group, for example because they are not
supported by the release type, etc.
If the register 402001/425345 (0x07D0/0x6300) is set to 0, the release will
respond to a group of objects featuring data that are contained in the valid
objects of the group. Since no data are available for the invalid objects, the
information in the register is not defined. These registers may contain
0x00000000, and a value of 0xFFFFFF may be used to represent an invalid
unsigned fixed-point object. The value 0x80000000 may be used to
represent an invalid signed fixed-point object.
NAN = 0x7FF20000 may be used to represent an invalid floating-point value
(NAN = not a number = invalid floating-point value). This makes it possible to
access a register block with a single read command, even if some of the
relevant registers are not implemented in this particular block, in order to
avoid having to use multiple read commands that contain only the
implemented registers. The application thus ensures the selection of the
implemented registers. The start register number must be a valid object.
If the start register number accesses an invalid object, exception code 02 will
be returned for the invalid data object regardless of this configuration setting.
The non-volatile register 402002/425346 (0x07D1/0x6301) is used to
configure the data transfer sequence of 32-bit floating-point data. If not equal
to 0 (default setting), the low-order word for the floating-point value will be
displayed first in the Modbus register range. If the register is set to 0, the
high-order word for the floating-point number will be displayed first in the
Modbus register range.
The non-volatile register 402003/425347 (0x07D2/0x6302) is used to
configure the data transfer sequence of 32-bit fixed-point data. If the value is
not equal to 0 (default setting), the low-order fixed-point word will be
displayed first in the Modbus register range. If the register is set to 0, the
high-order fixed-point word will be displayed first in the Modbus register
range.
The registers 402001/425345 to 402003/425347 (0x07D0/0x6300 to 0x07D2/
0x6300) are configured via the write function codes 06 or 16.
In order to support Modbus masters that can only access register 9999,
some Eaton registers that were originally assigned to registers above 9999
have been granted double access, both to the original register (to ensure
compatibility) and to a new assigned register below 9999. The format is
given as a low/high register number followed by (low 16/high 16 Modbus)
register addresses.
For example: 4xxxx/4yyyy (XXXX+1
16
/YYYY+1
16
).
￫
If a value is not equal to zero (default setting), any attempt to
access a group of data objects containing an invalid object will
return the error code 02.
