DDE and Fix32


Thread Starter


i'm trying to grab information from our fix32 database with my visual basic application using a dde client server that i have set up......

i am grabbing data from a slc 504 no prob in this application..... but am experiencing difficulty grabbing SQD data from fix...... any ideas?????
If u r using

1)Fix as a DDE Server and VB as DDE client

u have to use the controls in VB Form which supports DDE, for example.. Textbox control.
In the "Text" properties
DDEItem:(the Tagname in full)

Also, in the Fix SCU, DDEServer.Exe driver should be loaded in the I/O drivers.

2)VB as a DDE Server and Fix as DDE client
In the tag I/O Address field, u have to type in the syntax as -> Application:Topic!Item
For example -> Project1:Form1!Text1.text
where Project1 is the Exe name.
Also, u have to set the VB Form Property:
(this enables the Form in the VB application to supply to the other windows DDE environment!)
Also, in the Fix SCU, DDEClient.Exe driver should be loaded in the I/O drivers.

For both options.. The driver DMDDE.Exe should be loaded in the Fix SCU

This information may help u!

SQD means what????
iFIX DDE Local Addresses
DDE addressing syntax is used to transfer data from iFIX to other applications on the same computer. Refer to the following table for the syntax used to transfer real-time data.

Real-Time Data Syntax

String Part

(or Service) name

Topic name

Item name
Node:Tag.Field (A_)

Real-Time Data Syntax

An example of the syntax used to transfer real-time data is:

where DMDDE is the Application or Service Name, DATA is the Topic Name, and NODE1.AI1.A_CV is the Item Name.
DDE Addressing
A local DDE server is accessed using a three part address know as an ATI, or a remote reference formula if you are using Excel. The address consists of the application, the topic, and the item. The documentation for the DDE server that you are using provides the specific syntax you must use in order to access its data. The following is a general description of the parts of a DDE address:

Application — the name of the DDE server where the data resides. In many cases, the software program uses its name as the application name.

Topic — the name of the group of data on the DDE Server. The topic name can be the spreadsheet or file name containing the data to access.

Item — the individual piece of data to transfer. The item name depends on the method by which data is stored in the server application.


To access data in an Excel workbook, use the following syntax:

Excel allows you to create multiple sheets within a workbook. In this example, the DDE address retrieves the value in the first row and column of SHEET1 in the FILE.XLS workbook.

NOTE: iFIX can access any third-party software package that uses DDE addressing. Refer to your third-party software documentation for more information on the proper DDE address for your software package.

I/O addresses are used in process database blocks. When entering an I/O address, the application name can use up to 26 characters, the topic name can use up to 20 characters, and the item name can use up to 79 characters
DDE I/O Driver Configuration
To use DDE data in the process database, you must purchase and configure the DDE I/O driver. The DDE I/O driver can be installed as one of your I/O driver selections during software installation. The DDE driver requires the DDE Client Task to function properly. If you add the DDE driver during software installation, and an SCU file exists, the DDE Client Task, DDECLNT.EXE, is not added to the configured task list in the SCU.

Once installation is complete, ensure that the DDE Client Task has been added to the configured task list in the SCU. If it does not appear, add the DDE Client Task to your configured task list manually. Refer to the Setting up the Environment manual for instructions on adding a task to the configured task list.

Alternatively, you can delete the DDE driver from the SCU and then add it back manually. When you add the DDE driver manually, the DDE Client Task is automatically added for you.

Using DDE Client Support in the Database
iFIX DDE client support allows you to read and write information from another DDE application, a DDE device driver, or another SCADA node using the DDE I/O driver. Because the data is available in the process database, you can incorporate the data into your strategy to:

Pass data in chains.

Alarm on DDE data.

Trend DDE data.

You can enter a DDE address as an I/O address in any I/O-based database block. The data updates on a time-based or exception-based rate depending upon how you configure the scan time in the block. Do not use a one-shot scan time when you are configuring a block to use DDE data.

The following example demonstrates how to configure the Hardware Specifications section of an I/O-based block to access DDE information:

Device: DDE
Hardware Options:
Signal Conditioning:
In this example, the device driver entry (DDE), indicates that the source of the data is a DDE server. The DDE address entered into the I/O Address field requests data from the first row and column of Sheet1 of the Excel workbook, FILE.XLS. Signal conditioning is not performed on DDE data and the Hardware Options field is not used.

NOTE: Your operating system's International Number Format must be configured identically in the nodes sharing data. All iFIX applications use this configuration.

System Messages
The following table describes the system messages and corresponding explanations associated with the DDE server.

DDE System Messages

Error Code

iFIX is not running.

Invalid field.

Field's value not known or block may be off scan.

Invalid field.

Invalid field.

Network-related problem.

Session not established. Cannot find remote node.

Session with remote node has been lost.

Tag is not defined in the database.

Network-related problem.

Either waiting for data or node name is not in the network table.

Session not established. Cannot find remote node.

Invalid node, tag, or field entered, or problem returning data.

No communication established with DDE.

Invalid node, tag, or field entered, or problem returning data.

Could you please tell me how can I use VB as DDE Server? I want to use Textbox to deal with DDE.

Could you please advise how can I set VB form property, Source=True?

Looking forward to your prompt reply. Thanks a lot.

Best regards,