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OPC-DA

Capabilities

Capability	Support	Comment
OPC-UA protocol		See OPC-UA
Connection state monitoring of OPC-DA server		See Server monitoring connection state
Reading value by subscription from OPC-DA server		See Reading values using subscription
Writing value from OPC-DA server		See Writing values

Supported types

Concept

Overview

OnSphere allows you to easily read (Reading values using subscription) and write (Writing values) data on a OPC-DA server. The status of connection between OnSphere and the OPC-DA server is also monitored.

Here are the possible connection parameters for an OPC DA server :

OnSphere Type transformation

Opc Da Type	OnSphere Type
BSTR	TEXT
BOOL	BOOLEAN
I1	TEXT
I2	NUMBER
I4	NUMBER
UI1	NUMBER
UI2	NUMBER
UI4	NUMBER
R4	DECIMAL
R8	DECIMAL

Note

If a type is not in the above table it is not officially supported but it does not mean it won’t work.

Connect

Here are the possible connection parameters for an OPC DA Server :

Field	Description	Usage
classId	The class Id of the OPC DA Server	Tells which application to connect to on the Windows machine
progId	The programme Id of the OPC DA Server	Tells which application to connect to on the Windows machine
domain	The domain of the Windows machine you are trying to reach
passwordProvider	The OPC DA Server password
host	The host of the OPC DA Server

Note

It is recommended to use classId if possible. If the classId and the progId are provided the classId has priority.

Server monitoring connection state

Concept

The connection state between the OPC-DA server and a server can be read as a BOOLEAN value from the OPC-DA device in the OnSphere hierarchy (i.e. root.opc_da.server1 for example). If the connection is not working the state will be set to false.

Usage

A typical use case would be to monitor the status of an OPC-DA server

Reading values using subscription

Concept

OnSphere will read a specific itemId once the server is reachable (once the connection state value is set to true). Once it was read for the first time it will then subscribe to it and notice OnSphere when a change occurs. The module allows you to read an itemId by defining a owner.

When reading a value please refer to the correct OnSphere type following this table.

Usage

A typical use case would be to monitor a temperature of a boiler.

Writing values

Concept

The module allows you to write on an OPC-DA device on demand. OnSphere allows OPC-DA writing through callbacks: define your output and simply reference it in a callback.

When writing a value please refer to the correct OnSphere type following this table.

Usage

A typical use case would be to control the speed of a motor.