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3X Registers
(M80x/M81x/M84x)
From
firmware V5 - 18/06/03 only.
Internally, the M80x/M81x and M84x 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 with 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 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)]
Sample
Coding
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