Exercise 5: Creating a New Module (LI-101) from Scratch

In this exercise, you will use Control Studio to create from scratch a module to monitor the tank level. The module will have one analog input function block (to allow reading of the analog input signal) and one output, a promoted parameter. Promoted parameters are available under the Special Items palette. The promoted output parameter allows this value to be more easily accessed systemwide.

Four other changes will be made.

• The IO parameter of the analog input block will be edited to identify the Device Signal Tag for the level transmitter, LT-1.
• The OUT_SCALE parameter on the analog input block will be changed from the default value of 100 to 10,000 to reflect the 10,000-gallon capacity of the tank.
• The HI_HI_LIM value will be changed to 1000.
• History collection will be added to the PV of the AI block so that the tank level can be trended in the Process History View application.

To create a new module

1. In Control Studio, click the Main button, then click New. The New dialog box appears.

2. Click OK to accept the default settings in the New dialog.

Control Studio opens with a blank, untitled Function Block diagram.

To add and modify a function block for analog input

1. Select IO palette category. A list of function blocks related to I/O appears.
2. Select the Analog Input (AI) function block from the palette; drag-and-drop it onto the Function Block diagram.
3. To find out more about this function block, point to the AI block, click the right mouse button and select What's this? from the menu.

Tip To access detailed information, you can click the Books Online (Reference) icon at the end of the pop-up text. After reading about the function block, click the Close button in the Books Online window to quit that application and return to Control Studio.

4. Make sure the block is selected.
5. In the list of parameters, double-click HI_HI_LIM (or click the right mouse button and select Properties).
6. In the Properties dialog box, change the value to 1000 and click OK.
7. Double-click the IO_IN parameter.
8. In the Properties dialog box, enter the Device Signal Tag, LT-1 (for the level transmitter), and click OK. The system selects the default parameter.

In the Parameter list, note that the parameter named L_TYPE (linearization type) has a default value of Indirect. This must remain Indirect for you to be able to define the Engineering Units of the input.

9. To set the Engineering Units (EU) and the scale, double-click the OUT_SCALE parameter.

10. Modify OUT_SCALE as follows:

• Change the 100% scale from 100 to 10000 (for 10,000 gallons).
• For Engineering unit descriptor, select gal (for gallons).

11. Click OK.

For our example, we would like to make the output value easy to reference system wide. Promoting the parameter to the module level allows the value to be referenced throughout the system as LI-101/PV rather than LI-101/AI1/OUT.

To add a module-level parameter for output of the process value

1. Select the Special Items palette.
2. Select the Output parameter, click the right mouse button, and select What's This? from the menu to get a description.

3. Drag-and-drop the Output parameter onto the diagram to the right of the AI function block.

A Properties dialog box appears.

4. Change the parameter name to PV (for process value).

5. Select Floating point with status in the Parameter field, select I/O in the Parameter category field, accept the default status (it will be overwritten), and click OK.

The block named PV now appears on the Function Block Diagram.

To add history collection to the PV

1. Select the AI block in the Diagram View.
2. In the Parameter View list, click the right mouse button on PV and select Add History Recorder.

The Add History Collection dialog opens.

3. The path to the current value for the PV (AI1/PV.CV) appears in the Parameter field path box. (If this path does not appear here, click the Browse button and browse for it.)
4. Click Enabled.
5. Click Line as the Display Representation.

Note The line style can be changed in the Process History View application.

6. Use the default value of 60 seconds as the sampling period.
7. Click OK.

Later, we will assign the area (TANK-101) to the Continuous Historian subsystem, enable history collection on the workstation, and download the workstation in order to collect and view the historical data for the field values.

To connect the two blocks

1. Click the Out connector on the AI block and hold down the left mouse button. (The focus must be in Diagram View for this button to be active.)
2. While holding down the left mouse button, draw a line from the Out parameter on the AI block to the PV parameter.

The pencil changes to a * when you are over the right spot for making the connection.

Tip If you want to rearrange the diagram, click one of the function blocks and move it. The connector line moves and resizes automatically.

Your finished diagram should look like this: