Modbus Driver

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Introduction

Modbus is a communication protocol for PLC Devices openly published by Modicon (now part of Schneider Electric). Since its publication in 1979 Modbus has been widely adopted as a communication protocol for PLC Devices.

The Fernhill SCADA Modbus driver scans PLC Devices (or other types of device) for data using the Modbus communication protocol. The Modbus driver supports these variants of the Modbus protocol:

Fernhill SCADA Modbus Tags

The Modbus driver provides these tag types to support communication using the Modbus protocol:

Icon	Tag Type	Version	Description
	Modbus TCP Channel Tag	1.0	A connection to a Modbus device using the TCP/IP protocol.
	Modbus Serial Channel Tag	1.0	A serial port used for Modbus serial communications.
	Modbus Device	1.0	A device supporting the Modbus protocol.
	Modbus Register Block Tag	1.0	A block of registers read from a Modbus device.

To configure Fernhill SCADA to communicate with a Modbus Device, do the following:

1. Create and configure one of the following channel tags depending on your communication requirements:
   • Modbus Serial Channel Tag
   • Modbus TCP Channel Tag
2. Create a Modbus Device Tag. Configure these properties of the Modbus Device Tag:
   • Set the Channel property of the Modbus Device Tag to the channel tag you created in step 1.
   • Set the Unit property to match the address of the Modbus Device.
   • Set the DataAddressFormat property to match the address format of the Modbus Device.
   • For the most Modbus Devices, the other configuration properties can be left at the default values.
3. Create I/O Data Point Tags to represent the data in the Modbus Device. For each I/O Data Point Tag you create:
   • Set the IODataSource property to the name of the Modbus Device Tag you created in step 2.
   • Click the browse button to set the address of the I/O Data Point Tag.

The Serial Device Configuration Walkthrough provides instructions on configuring tags manually.

Fernhill SCADA I/O Data Point Tags

You can use these I/O Data Point Tags to represent individual data points in the PLC:

Icon	Tag Type	Version	Description
	I/O Analog Data Point Tag	3.12	Maps an Analog Data Point Tag to an external data source.
	I/O Digital Data Point Tag	3.12	Maps a Digital Data Point Tag to an external data source.
	I/O Word Data Point Tag	3.12	Maps a 16-bit Word Data Point Tag to an external data source.
	I/O Double Word Data Point Tag	3.12	Maps a 32-bit Double Word Data Point Tag to an external data source.
	I/O Long Word Data Point Tag	3.48	Maps a 64-bit Long Word Data Point Tag to an external data source.

Autodetect Wizards

The Modbus driver supports these Autodetect Wizards:

Further Information

Modbus Protocol

For a description of the Modbus Protocol.

Standard Modbus Data Address

For a description of how a Standard Modbus Data Address is constructed in Fernhill SCADA.

Enron Modbus Data Address

For a description of how an Enron Modbus Data Address is constructed in Fernhill SCADA.

DirectLogic Data Address

For a description of how an DirectLogic Data Address is constructed in Fernhill SCADA.

Modbus Serial Autodetect Wizard

To learn about the Modbus Serial autodetect wizard.

Modbus TCP Autodetect Wizard

To learn about the Modbus TCP autodetect wizard.

Serial Communications

For background information on serial communications.

Fernhill SCADA Drivers

For information about other drivers available in Fernhill SCADA.

Glossary

For the meaning of terms used in Fernhill SCADA.

Fernhill SCADA Version 3.95 (20230529.2). Copyright © 2012-2023 Fernhill Software Ltd: All rights reserved.