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Measurement Registers (3X and duplicated 3X)
Internally, the M850
3X registers are duplicated in the 4X register
area from address 42001,
(internal register offset 2000 (07D0h)).
This allows PLCs
that can’t read floating point data in the 3X area to retrieve the measurements
from the 4X area.
The registers are listed below in their Modbus addresses.
The data held at these addresses are Read-Only.
3X registers are read using function 04h.
4X registers are read using function 03h.
A sample read packet using code 4 to access the 3X registers will look like this:-
[Node][04][start address][No. of Double Registers Requested][CRC(2 bytes)]
e.g. To read line to neutral voltages on node 23h:-
[23h][04h][0006h][0006h(3, 4 byte regs)] [CRC(2 bytes)]
The node’s return packet will look like:-
[23h][04h][0Ch][12 bytes of data = 3 floating point numbers] [CRC(2 bytes)]
A sample read packet using code 3 to access the 4X registers will look like this:-
[Node][03][start address][No. of Double Registers Requested][CRC(2 bytes)]
e.g. To read line to line voltages on node 23h using the duplicated measurements
in the 4X area:-
[23h][03h][07D0h][0006h(3, 4 byte regs)] [CRC(2 bytes)]
The node’s return packet will look like:-
[23h][03h][0Ch][12 bytes of data = 3 floating point numbers] [CRC(2 bytes)]
The list below is the default order of the 3X registers.
The order can be altered using the Multiview program, supplied on request or downloaded from our
website,
or by a suitable SCADA program.
Sample Coding
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