Modbus Driver

Help Contents

Introduction

Modbus is a communications 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 communications protocol for PLC Devices.

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

ProtocolDescription
Modbus RTU8-bit serial binary protocol
Modbus ASCII7 bit serial ASCII protocol
Modbus TCPTCP/IP protocol
Modbus RTU over TCPModbus RTU over TCP/IP

Fernhill SCADA Modbus Tags

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

IconTag TypeVersionDescription
Channel IconModbus TCP Channel Tag1.0A connection to a Modbus device using the TCP/IP protocol.
Channel IconModbus Serial Channel Tag1.0A serial port used for Modbus serial communications.
PLC Device IconModbus Device1.0A device supporting the Modbus protocol.
Register Block TagModbus Register Block Tag1.0A block of registers read from modbus device.

The Modbus tags you configure tells the driver how to interact with Modbus PLC Devices.

The Serial Device Configuration Walkthrough provides step by step 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:

IconTag TypeVersionDescription
Analog Data Point TagI/O Analog Data Point Tag3.12Maps an Analog Data Point Tag to an external data source.
Digital Data Point TagI/O Digital Data Point Tag3.12Maps a Digital Data Point Tag to an external data source.
Word Data Point TagI/O Word Data Point Tag3.12Maps a 16-bit Word Data Point Tag to an external data source.
Double Word Data Point TagI/O Double Word Data Point Tag3.12Maps a 32-bit Double Word Data Point Tag to an external data source.
Long Word Data Point TagI/O Long Word Data Point Tag3.48Maps a 64-bit Long Word Data Point Tag to an external data source.

Autodetect Wizards

The Modbus driver supports these Autodetect Wizards:

WizardDescription
Modbus SerialSearches serial ports for PLC Devices supporting the Modbus protocol.
Supports both RTU and ASCII variants.
Modbus TCPSearches an Ethernet network for PLC Devices supporting the Modbus TCP protocol.

Further Information

Modbus Protocol

For a description of the Modbus Protocol.

Modbus Data Address Format

For a description of how Modbus data addressing works 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.