ROOTECH ACCURA 7500, User Manual, Page: 11 / 76

Page 11
Chapter 1 Serial Communication
Serial Communication
Accura 7500 has a RS-485 port supporting multi-drop operations for communication between
Master and Slave devices. In order to communication with host system, Accura 7500 supports
Modbus RTU protocol for general users.
Modbus RTU protocol is used for connection with automation equipment such as PC and PLC, and
as an industrial standard, it allows users to efficiently transfer measurement and setup data between
master[PC, PLC, or etc.] and slave[Accura 7500] devices.
Multi-drop Mode for Communication between Master and Slave Devices

Every communication on the network is based on communications between Master and
Slave systems.

A master device sends and controls all information on the communications loop.

A slave device responds only when there is a request from a master device.

All communications occur in the form of packets, which consist of bytes.

All packets transmitted by the master device are requests. All packets transmitted by the
slave device are responses.

In communication between Master and Slave devices, when the master device sends a
request, only one slave device among connected slaves responds.
Modbus RTU protocol

Standard protocol for general users

It is recommended to use Modbus RTU protocol for communication with Rootech’s products.

It is designed according to the Modbus RTU specifications of Modicon(now Schneider) , Inc.

It allows for selective communications by using address maps for measurement data and
setup parameters of relays.

It supports the basic communication driver used for communication with PLC devices or
automation programs as a common industrial protocol.