The logic is the station's program or purpose. A Niagara AX installation professional or systems integrator creates the logic in each station on each platform that is deployed. The installation professional uses the Niagara AX Workbench software to create the logic for the station.
Please refer to the following illustration while reading this section.
The installation or maintenance professional drags components from the palettes within the Niagara AX Workbench into the station as needed. Each component performs a simple or complicated computation upon its properties. Properties are data values on a component.
Properties can be assigned values directly from within the workbench. Alternatively, the installation professional can draw a line from a property on one component to a property on another component. This is called a link. The Niagara AX station program ensures that whenever a value on the source property changes, the result flows across the link and updates the property on the other side of the link. This causes the latter component to reprocess its own computations and possibly update the values for its other properties as a result of the change to its
In short, properties can be assigned values directly from within the Niagara AX Workbench, or by being linked to -- from another property that changes, or by a user from a web browser (please read further about "Px" Pages for more information).
Driver Components: Niagara AX drivers feature special software components whose properties display data values from some external equipment that is connected to the platform computer on which the Niagara AX station is running. When the property values are changed from within Niagara, these special components update the corresponding data values in the external equipment.
The special components that feature properties and synchronize data values between a Niagara AX station and some external equipment are called driver control points.
Components sometimes have actions on them. An action is a way of telling the component to perform a special computation or to do something special. Actions are identified by names that usually describe the special computation that the component will take if the action is invoked. Actions can be invoked directly from within the Niagara AX Workbench or from a web browser (please read further about "Px" Pages for more information). To view or invoke an action from within Workbench, right-click a component either in the Nav tree or in the Wire Sheet, a pop-up menu will appear, hover over the Actions side-menu. All available actions on the component will appear in the Actions side-menu. If the Actions side-menu is grayed-out, then that means that there are no actions available for the selected component.
Niagara AX drivers feature special software components. The actions on these special component's can be programmed so that when invoked, they cause some behavior to occur within the equipment that is connected to the platform computer on which the station is running. Typical actions might be called Reboot, Set Time, or Set Date. When invoked on a special component in your driver, it might reboot any equipment that the component represents, set the time in the equipment, or set the date.
The special driver components that would likely feature these actions are called driver devices and driver control points.
Components sometimes have topics. A topic is an event that the component fires when the component detects that a certain condition has occurred, whatever the certain condition might be depends on the component itself.
Niagara AX drivers feature special software components. The topics on these special component's can be programmed to fire whenever the driver detects that some behavior has just occurred inside the external equipment. This is one way of allowing a Niagara AX station to know when something occurs inside the external equipment.
In general, topics are not used very often in drivers. Here are a few typical examples though of when a driver might make use of topics:
- Depending on your driver's abilities, you could add a topic called Rebooted to a driver device component. Your driver could fire the rebooted topic whenever it detects that the corresponding unit of equipment has been power-cycled or otherwise rebooted.
- Depending on your driver's abilities, you could add a topic called Time Changed to a driver device component. Your driver could fire the Time Changed topic whenever it detects that the corresponding unit of equipment has experienced a change to its internal clock.
- Depending on your driver's abilities, you could add a topic called Date Changed to a driver device component. Your driver could fire the Date Changed topic whenever it detects that the corresponding unit of equipment has experienced a change to its internal calendar.
This assumes that your external device supports such a notion.The special driver components that would likely feature these topics are called driver devices and driver control points.
A Niagara installation professional uses the Workbench to edit the logic in a station. The installation professional drags components into the station, as needed, to define the station's behavior. The installation professional draws lines from properties on one component to properties on another component. These lines are called links. Whenever the value of a property changes on one component, the value is automatically propagated across the link to the value of the corresponding property that is on the other side of the link.
Driver control point components are virtually tied to a data value that is in a unit of equipment that the driver communicates with. The value for the property named out on the driver control point reflects the value that is really in the unit of equipment that the driver communicates to. One or more links can be drawn from the out property to feed any other logic in the station. Likewise, driver control points that are writable, feature several properties whose names start with in. The value flowing through the logic that is linked to the in property with the lowest index will be transferred into the proper unit of equipment for the driver, thereby changing a setpoint or other setting in the corresponding equipment.
The Niagara installation professional can also draw a link from any property on a component to any action on another component. Whenever the property changes on the first component, the action is invoked on the corresponding component, thereby causing the corresponding component to perform the special computation or behavior described by the action's name.
The Niagara installation professional can also draw a link from any topic on a component to any action on another component. Whenever the topic is fired on the first component, the corresponding action on the other component is invoked, thereby also causing the corresponding component to perform the special computation described by the action's name.
Niagara AX installation professionals create Px-Pages to provide or gain feedback from other web users. The web users are those who will ultimately be interacting with the equipment that the driver provides access to. Px-Pages are assigned a URL (Internet address) that can be viewed from a web browser or the Workbench software. Niagara AX installation professionals can add one or more Px-Pages to any component. To do this, they right-click a component from the Nav Tree in Workbench and select the New View item from the pop-up menu.
After adding the new Px-Page to the component, the main viewing area of the Workbench will become like a graphic editor. The Niagara installation professional will drag one or more of the other components from the station (under the Nav tree in Workbench) and drop them into the Px-Page editor. When this happens, the editor prompts the installation professional and asks him or her to choose one or more properties or actions from the corresponding components that were dropped onto the graphic. Then text boxes, images, buttons, or other graphical items appear on the graphic. These graphical items are called Px-Widgets.
The Niagara AX installation professional then drags these widgets around the screen and possibly edits them to change their color, font, size, etc. As previously mentioned, the Px-Page is assigned a URL (special Internet address) that can be visited from a web browser. These text boxes, images, buttons, etc. can be viewed or manipulated directly from a web browser to gain real-time access to the equipment over the Internet.
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