Chapter 22 - Testing Your Progress of Day 3

In today's lesson you created a write request, a write response, and a write parameters structure. You may have also created a point-auto request and a point-auto response. You may have also added some frozen properties to your point id. By doing all of this, you have supplied enough information for the developer driver framework to automatically update the data values in your field-device if and when a corresponding control point component (with a proxy extension from your driver) is controlled or scheduled from within Niagara AX.

We encourage you to follow the same procedure that we specified at the conclusion of yesterday's lesson to test the control points in your driver. To test writing your driver's control points, you may right-click any writable control point (for example, a Numeric Writable) under your device's point device extension from the workbench (provided that it is connected to your test station), expand the actions menu, choose emergency override, enter a value in the window that pops up, and click Ok. To then auto your control point, right click the point again but choose Emergency Auto from the actions menu.

Writable Driver Control Points - Overview

Driver control points that are writable update data values in a field-device. Writable control points feature an input priority scheme. They feature 16 control inputs. If you recall back to the discussion before day 1, we introduced you to the concept of logic links. Niagara AX installation professionals can link to 14 of the control point's inputs (inputs 2-7 and inputs 9-16). They can design logic that feeds any or no value through any links that they create to any of the available priority inputs.

Inputs 1 and 8, as well as the fallback value, are reserved for the following items that appear on the control point's actions menu.

Emergency Override: Sets the control value for the most critical priority -- priority level 1.
Emergency Auto: Clears the control value for the most critical priority -- priority level 1.
Override: Sets the intermediate control value -- priority level 8.
Auto: Clears the intermediate control value -- priority level 8.
Set: Sets the fallback value. This value takes effect if no value is being supplied to any of inputs 1-16.

Driver control points automatically use your driver to set the data value in the field-device equal to the input value that is provided at the priority of the index closest to input one. If no values are provided to any of the sixteen input properties then the driver control point will set the data value equal to the fallback value (if one is specified) on the property sheet of the control point.

If no fallback value is provided and if no input values are provided, then the driver control point will not modify the particular data value in your field-device. Whenever a transition occurs within the station that causes this scenario to occur, the driver control point will ask your driver to auto the data value in the field-device. Your driver may or may not need to take any special action during this scenario. If you specified a point auto request then the dev driver framework will automatically transmit it through your field-bus in this scenario.

We hope that this discussion will allow you to test the write and auto functionality that you created during today's lesson.

NOTE: You will need to follow the procedure outline in the conclusion for Day 2. However, make sure that you add a writable control point from your driver's point manager. Writable control points are Numeric Writable, Boolean Writable, Enum Writable, and String Writable. We recommend that you start testing with a Numeric Writable and/or a Boolean Writable.

After adding a writable, driver control point to your station, right-click the writable control point, hover over the actions side-menu, choose the Emergency Override action, and specify a value on the dialog that appears. The developer driver framework and the Niagara AX framework will work together to transmit the byte array from an instance of your driver's write request, as described during today's lesson.

After running tests to write a value to one your driver's control points, please consider running tests to auto your driver's control point. To do this, right-click the writable control point, hover over the actions side-menu, and choose the Emergency Auto action. The developer driver framework and the Niagara AX framework will work together to transmit the byte array from an instance of your driver's auto request, as described during today's lesson.

Please refer to the conclusion of Day 2 for illustrations about how to use your driver's point manager to create driver control points.