RS485 – Modbus

The device has opto-isolated RS485 interface with support of Modbus RTU. It is dedicated to energy meter, voltage meter and any Modbus device like PLC which support Modbus RTU protocol. The device supports multiple Modbus devices with separate address range. It is possible to directly send and receive any value of register from server. Please follow proper connection of A and B signals from device to A and B signals in power meter. If the polarity is reversed there will be no data transmission. All modbus configuration like baud-rate, parity, address available in internal website. 

Serial – Configuration of serial communication

In this section are RS485 parameter configuration: baud rate, data bit, parity and stop bit.

Parameter Option/range
Baudrate 2400 to 460800
Data bit 8, 9
Parity None, Even, Odd
Stop bit 1, 1.5, 2

AG-811 www modbus serial parameters


Req. dev. – Request device log

In this section is visible log of modbus devices. In this tab is optional feature to make support for Selec® company meter without necessity to set modbus device details. In window the reply from Selec® device will be visible. Now 2 models of meters are supported MFM383 and  EM2M.

AG-811 www modbus request

Devices – Modbus devices

Modbus devices configuration of modbus devices connected to Gateway. Configuration of: device ID, register, endian, start address, offset address, registers, timeout. It can add multiple devices up to maximum 16.

multiple devices up to maximum 16.



Details information



To activate device configuration 


Modbus Device ID

The ID of modbus device. 01 up to FF.


Register structure

8 bit UINT, 16 bit UINT, 32 bit UINT, 8 bit INT, 16 bit INT, 32 bit INT, 32 bit float, 16 bit HEX, 32 bit HEX, Array HEX


Endian Structure



Start address

First Modbus register address


Offset address

Offset address for add or subtract of actual query address, according to slave device data storage system


Number of registers

How many registers needed to query


Timeout [ms]

Response time-out for query

AG-811 www modbus device

Example for query: 01 04 00 00 00 28 F0 14
In this example F0 14 is checksum CRC-16 big endian.

AG-811 www modbus device example