Specifications

A sample write 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][000Ch][12 bytes of data = 3 floating point
numbers] [CRC(2 bytes)]
The list below is the default order of the 3X registers in
M550. The order can be altered using the Modbus Regis-
ters Tool Program, (see section 4), or by a suitable SCADA
program.
Modbus Add. Register Add. Register Name Order No.
30001 (0x00) V L1-2 1
30003 (0x02) V L2-3 2
30005 (0x04) V L3-1 3
30007 (0x06) V 1* 4
30009 (0x08) V 2* 5
30011 (0x0A) V 3* 6
30013 (0x0C) I 1 7
30015 (0x0E) I 2 8
30017 (0x10) I 3 9
30019 (0x12) W Sum 10
30021 (0x14) VA Sum 11
30023 (0x16) VAR Sum 12
30025 (0x18) PF Avg 13
30027 (0x1A) WHr (IMP) 14
30029 (0x1C) VArHr (IMP) 15
30031 (0x1E) Hz 16
37