MODBUS PROTOCOL
The Series 4000 Energy Meter can communicate by means of the ModBus protocol as described below:
When the meter communicates with MoBus, it uses the RTU mode (Remote Terminal
Unit). Each 8-bits byte in a message contains two 4-bits hexadecimal characters.
MoBus RTU Protocol, Default Configuration: 001 / 9600 / 8 bits / N / 1 bit
Baud Rates: 1,200 / 2,400 / 4,800 / 96,000
The format for each byte in RTU mode is:
Code 8-bits binary, hexadecimal 0-9, A-F
Two hexadecimal characters
contained in each 8-bits field of
the message.
Bits per Byte 8 data bits
Error Check Field Cyclical Redundancy Check (CRC)
ModBus Functions:
Function 01 Reading of the Relay State
Function 03 or 04 Reading of n words (16 bits-2 bytes)
This function permits to read all the electrical
parameters. Each parameters is 32-bits long, hence
two words are required to inquiry for a parameter. (4
bytes-xx xx xx xx).
EXAMPLE
Inquiry
OA Meter peripherals number, 10 in decimal
04 Reading function
00 00 Initial address (first register)
00 0A Number of registers to be read
7176 CRC character
Answer 0A 04 14 00 00 08 4D 00 00 23 28 00 00 0F A0 00 00 00
90 00 00 00 60 2E
0A Meter number, 10 in decimal
04 Reading function-the one used for the inquiry
14 Bytes received (20)
00 00 08 4D V X 10 (register 00 Hex), in decimal 212.5 V
00 00 23 28 mA, in decimal 9000 mA
00 00 0F A0 W, in decimal 4000 W
00 00 00 60 PF X 100, in decimal 96 PF
CB 2E CRC character
Reading digital outputs (relays)-Function 01:
Inquiry PP0100000008CRC (PP = peripheral No.)
Answer PP0101XXCRC
Where XX (hexadecimal byte)→translated to binary ║b7║b6║b5║b4║b3║b2║b1║b0║
bit b0 = relay 1. (1 = ON; 0 = OFF)
bit b1.= relay 2. (1 = ON; 0 = OFF
