- 2 -
SDM530-MT smart meter to return a Modbus Protocol exception message. However, for
compatibility with some SCADA systems, SDM530-MT Smart meter will response to any single
input or holding register read with an instrument type specific value.
The SDM530-MT can transfer a maximum of 40 values in a single transaction; therefore the
maximum number of registers requestable is 80. Exceeding this limit prompts the SDM530-MT
to generate an exception response.
Data transmission speed is selectable between 1200,2400, 4800, 9600.
1.2 Input register
Input registers are used to indicate the present values of the measured and calculated
electrical quantities. Each parameter is held in two consecutive16 bit register.The following
table details the 3X register address, and the values of the address bytes within the message.
A (*) in the column indicates that the parameter is valid for the particular wiring system. Any
parameter with a cross(X) will return the value zero. Each parameter is held in the 3X registers.
Modbus Protocol function code 04 is used to access all parameters.
For example, to request: Amps 1 Start address=0006
No. of registers =0002
Amps 2 Start address=0008
No. of registers=0002
Each request for data must be restricted to 40 parameters or less. Exceeding the 40
parameter limit will cause a Modbus Protocol exception code to be returned.
1.2.1
SDM530-MT
Input Registers
Address
(Register)
SDM530-MT
Input Register
Parameter
Modbus
Protocol
Start
Address
Hex
3
Ø
Description
Units
Hi
Byte
Lo
Byte
4
W
30001
Phase 1 line to neutral volts.
Volts
00
00
√
30003
Phase 2 line to neutral volts.
Volts
00
02
√
30005
Phase 3 line to neutral volts.
Volts
00
04
√
30007
Phase 1 current.
Amps
00
06
√
30009
Phase 2 current.
Amps
00
08
√
30011
Phase 3 current.
Amps
00
0A
√
30013
Phase 1 power.
Watts
00
0C
√
30015
Phase 2 power.
Watts
00
0E
√
30017
Phase 3 power.
Watts
00
10
√
30019
Phase 1 volt amps.
VA
00
12
√
30021
Phase 2 volt amps.
VA
00
14
√
30023
Phase 3 volt amps.
VA
00
16
√
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