11.5 Adding an Analog Output Tag to Represent the Feed Time

As per the system plan, your client requires the ability to manually set the chemical feed time in order to regulate the concentration of the chlorine solution. An Analog Output tag will provide this function in your application.

Acceptable feed times are between 5 and 20 seconds. The following steps will guide you through the process of creating an analog output tag.

 

1.  Ensure that the tag browser is open

2.  Select Analog Output from the Types drop-down list and click the New button.

3.  Enter "AO40_1" in the Name field and press Enter.

4.  Ensure that "Chlorination Unit" is selected in the Area drop-down list (or the area entry you configured for the tags associated with the Chlorination Unit application page).

5.  Enter "Feed Time" in the Description field and press Enter. The completed ID tab should appear similar to Figure 145.

Figure 145

6.  Click the I/O tab.

7.  Select the "Modbus1 Virtual Modicon PLC" as the I/O driver.

8.  Enter "40003" in the Address field.

9.  Enter "sec" in the Engineering Units field. The completed I/O tab should look like Figure 146.

Figure 146

10. Open the Scaling tab.

11. Enter "5" in the Scaled Process Data Min field. This is the minimum value that can be entered for the feed time of the dry chemical feeder.

12. Enter "20" in the Scaled Process Data Max field. This is the maximum value that can be entered for the feed time of the dry chemical feeder. The completed Scaling tab should appear similar to Figure 147.

Figure 147

13. Click the OK button. The new analog output tag is created and appears in the Tag Browser.

Now that all of the tags specific to the chlorination system have been added, you can proceed to draw them on the Chlorination Unit application page.