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The DDE (Dynamic Data Exchange) protocol is used by a wide variety of software to allow data transfer and control between applications.

Hexatec software fully supports the DDE protocol as both Client and Server.  Allowing connections to be made to a wide range of DDE  communicating software.

DDE Client

I/O tags can be configured to communicate with a DDE Server, making data transfer to and from applications, such as Microsoft Excel, simple. By default, connection can be established by entering Server, Topic and Item(s) fields for a group of data tags.  Optional settings allow for different data delimiters.

By using the DDeExecute routine within a Hexatec application, commands available within server can also be triggered.  This makes it possible to control many other applications from within a SCAN1000 or Saturn project.

DDE Server

Hexatec software can respond to DDE client requests, including data transfer and execute commands.

Individual projects can be accessed independently, using DDE and virtually all system Object-properties  may be accessed.  For data tag objects, this includes the value and quality properties.

A powerful DDE command execution system allows clients to control the functionality of Saturn/SCAN1000 application, if required.  Internal script routines can also be invoked directly and object properties and methods accessed as required.  This makes it possible to integrate Hexatec software with other systems with ease.

Background

Originally designed by the Microsoft Excel (spreadsheet) development team and trialled before Window 2 was released, it allowed data to be directly entered into Excel from a variety of sources.  After series of improvements, it has been implemented in many different products.

As with other communications / data transfer protocols, DDE uses a client - server model, where a client application establishes communications to a server application and then performs actions such as data request, command execution, etc.  One such action is a, so called, 'hot link', where a server is asked to update the client as and when the server has new data available, avoiding the need for constant, unnecessary data refreshes.  Hot linked data is automatically updated.

DDE data points are defined using a text based Server-Topic-Item naming convention, making interconnections simple to configure.  'Server' is normally the name of the application, 'Topic' is an area within the server and 'Item' refers to an individual data point.   Data values can be written (poked) from SCAN1000, using this method.

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