Rs-485 communication protocol, Overview, Modbus rtu protocol – Bacharach AGM300 User Manual

Page 75: Rs-485, Ommunication, Rotocol

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Instruction 3015-4275

67

RS-485 Communication Protocol

Overview

The following instructions are intended as a guide for integrating the AGM300 network into a Building
Management System. If you are unfamiliar with complex systems of this type, it is recommended that you
contact Bacharach for technical assistance.

MODBUS RTU Protocol

The AGM300 monitor communicates with master devices (such as the ADM800 or a Building Management
System) over the RS-485 serial interface. The monitor is configured with a two wire RS-485 serial bus, and
therefore, data transmission occurs in ‘half-duplex’ mode. Consequently, only one device may be in transmit
mode at any given time.

Programmers should refer to the MODBUS Protocol Reference Guide for details and more comprehensive
instructions. The guide is available on the Modicon web site at:

http://www.modicon.com/techpubs/TechPubNew/PI_MBUS_300.pdf

Specific communication software is available at:

http://www.bacharach-inc.com/downloads.htm

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