Defining Variable Types

Cascade Connect: Version 4.0
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# 8.2. Defining Variable Types

We classify data into two main types when we are configuring a Windows client application. The first type is for read-write points that are used to display data both coming from and going to the data server. The second type is for read-only points that are only ever used to display data coming from the data server.

## 8.2.1. Read-Only Variables

Read-only variables used within an InTouch application may be defined as any type of variable within the InTouch internal database. The data point may be defined as memory real, memory integer, one among several group variables, etc. When Cascade Connect sends a new data value for one of these variables to InTouch with a DDE POKE message, the InTouch database will accept the new value without question.

| Only points sent from InTouch to the data server need to be defined as DDE type tags.

## 8.2.2. Read-Write Variables

Points to send from InTouch to the data server must be defined as DDE type tags. DDE tags can be:

- DDE Discrete

- DDE Integer

- DDE Real

- DDE Message

## 8.2.3. Example DDE variable definition

To define a data point as a DDE tag within the InTouch internal database, follow these instructions:

1. In the InTouch WindowMaker program select Special, then Tagname Dictionary. The Dictionary - Tagname Dictionary window will appear.

   Figure 8-2. The InTouch tagname definition screen

2. Click the New button and enter the new tagname in the Tagname field. As an example we will define the variable `output1` as a DDE Real tag that is to be written to the data server.

3. Click on the Type button and select DDE Real.

4. You may want to enter a comment.

5. Click on the DDE Access Names button and select cascade. This tells InTouch that this tag is associated with the Cascade Connect DDE channel.

6. Ensure the definition of the point is set to Read Write and the check-box at the lower right corner called Use Tagname as Item Name is selected.

7. Click Done when finished.

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