3. InTouch Configuration

Create a tag in the InTouch Tagname Dictionary called input1. You can make this tag a Message, Analog or Discrete type, but remember to select an "Indirect" type tag. In our example we make our data point an "Indirect Message" type.

Create tags called a@input1 and b@input1. These tags can be configured as either Memory or DDE type tags. For our example, we will not be sending data back to QNX using these tagnames so we do not need to configure them as DDE. We will configure these tags as Memory Messages.

Create a point called domain. This point should be configured as a Memory type tag. We will choose to make this tag a Memory Message. This tag will contain a value that indicates the current active datahub domain.

Create two more tags called db_a_up and db_b_up. These tags should be configured to be Memory Discrete type tags. When Cascade Connect starts, it will connect to the first available Cascade DataHub listed in its configuration file. We will be starting two Cascade Connect programs in Windows, one for datahub a and one for datahub b. When the Connect Server successfully attaches to the Cascade DataHub it sends a message to Cascade Connect telling it that the link to the datahub is established. This message is in the form:

    db_domain_name_up = 1

In our example, two messages will be sent to InTouch, one from each Cascade Connect. These messages will be db_a_up = 1 and db_b_up = 1. In the InTouch tag datahub, the value for these tags will be set to 1. If the link to the Cascade DataHub is ever broken, Cascade Connect will send a message (db_a_up = 0), which tells the Windows client that the link has been broken. This is the mechanism that allows InTouch to switch between datahubs when the link to one datahub is lost.

Now we need to create a Data Change Script (using the Special ==> Scripts ==> Data Change Scripts selection in the Window Maker menu bar).

1. In the Tagname field, type domain

2. Click on the Add button.

3. In the Script field, type:

       input1.Name = domain + "@input1";

   For all of the data points being transmitted from QNX you will need to duplicate this line in the domain Data Change Script. For example, you may be sending 50 data points from QNX. You must create an entry in the domain Data Change Script for each of the 50 points, for example: tank100_level.Name = domain + "@tank100_level"; motor23_amps.Name = domain + "@motor23_amps"; gatevalve1_pos.Name = domain + "@gatevalve1_pos"; gatevalve2_pos.Name = domain + "@gatevalve2_pos"; ... Remember that you will need to create three InTouch tags for each data point sent from QNX. One point will be the tag used in the InTouch system (e.g. input34) and the other two will be used by InTouch to determine the source of the data (e.g. a@input34 and b@input34).

Now create another Data Change Script as follows:

1. In the Tagname field, type db_a_up.

2. Click on the Add button.

3. In the Script field, type:

       IF db_a_up == 1 THEN
          IF db_b_up == 0 THEN
             domain = "a";
          ENDIF;
       ELSE
          IF db_b_up == 1 THEN
             domain = "b";
          ENDIF;
       ENDIF;

We now need to create a similar Data Change Script for datahub b, as follows:

1. In the Tagname field, type db_b_up.

2. Click on the Add button.

3. In the Script field, type:

       IF db_b_up == 1 THEN
          IF db_a_up == 0 THEN
             domain = "b";
          ENDIF;
       ELSE
          IF db_a_up == 1 THEN
             domain = "a";
          ENDIF;
       ENDIF;

We have to create a DDE channel for each of the two Cascade Connect programs. These channels are used to send data between Cascade Connect and InTouch. You may have already created a DDE channel for your original Cascade Connect development. In that case you would simply add another channel to accommodate the second Cascade Connect program. For this description, we will assume that two DDE channels need to be defined. DDE Channels are defined and configured from within InTouch as follows:

1. Select Special ==> DDE Access Names from the Window Maker menu bar.

2. Click on the Add button.

3. For the Access Name, type cascade1.

4. For the Application/Server Name, type cascade1.

5. For the Topic Name, type data.

We need to repeat this process for the second DDE Channel as follows:

1. Select Special ==> DDE Access Names from the Window Maker menu bar.

2. Click on the Add button.

3. For the Access Name, type cascade2.

4. For the Application/Server Name, type cascade2.

5. For the Topic Name, type data.

We have found that in our own tests that we need to change the DDE retry timeout settings in order to make InTouch start the two Cascade Connect programs. This is done as follows:

1. Select Special ==> Configure DDE from the Window Maker menu bar.

2. In the Retry Initiates: field, type 60.

We now need to configure InTouch so that it starts the two Cascade Connect programs when the user starts the InTouch application. This can be done by creating an Application Startup Script as follows:

1. Select Special ==> Scripts ==> Application Scripts from the Window Maker menu bar.

2. In the Condition Type field, select On Startup

3. In the script field, type:

       StartApp "C:\cascade3\cascade.exe -i c:\cascade3\indir1.ini"
       StartApp "C:\cascade3\cascade.exe -i c:\cascade3\indir2.ini"