Fernhill SCADA Modbus Protocol Driver

Modbus Driver

Introduction

Modbus is a communications protocol for Programmable Logic Controllers (PLCs) openly published by Modicon (now part of Schneider Electric). Since its publication in 1979 Modbus has been widely adopted as a communications protocol for PLCs.

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

Protocol Description
Modbus RTU 8-bit serial binary protocol
Modbus ASCII 7 bit serial ASCII protocol
Modbus TCP TCP/IP protocol
Modbus RTU over TCP Modbus RTU over TCP/IP

Fernhill SCADA Modbus Tags

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

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

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

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

Fernhill SCADA IO Data Tags

You can use these IO Data Tags to represent individual data points in the PLC:

Icon Tag Type Version Description
Analog Data Tag IO Analog Data Tag 3.12 Maps an analog tag to an external data source.
Digital Data Tag IO Digital Data Tag 3.12 Maps a digital tag to an external data source.
Word Data Tag IO Word Tag 3.12 Maps a 16-bit unsigned integer tag to an external data source.
Double Word Data Tag IO Double Word Tag 3.12 Maps a 32-bit unsigned integer tag to an external data source.

Autodetect Wizards

The Modbus driver supports these Autodetect Wizards:

WizardDescription
Modbus Serial Searches serial ports for PLCs supporting the Modbus protocol.
Supports both RTU and ASCII variants.
Modbus TCP</td> Searches an Ethernet network for PLCs 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.