Templates

Templates are a simple but a very powerful feature in Ignition that you can use with the Vision windows. The power comes from the ability to modify only the template in one location while affecting all of the instances used throughout the project. HMI and SCADA systems typically have a lot of repetitions in their screens. You might use a group of the same components over and over within your project. The data driving each set of graphics is different, but the graphics themselves are copies of each other. You can make a single template and use instances of the template over and over again.

When using templates, you define the graphical display in one place, called the master template. You then use this master template many times in your project on multiple windows, thus making a number of template instances. Any changes made to the master template are then reflected in all of the template instances. Using templates early in your project development for any repeating displays can save a significant amount of time later on.

Without templates, the only way to do this is to copy-and-paste the components then re-bind them each time you want another. This is simple, and it works, but it can cause major headaches and time consuming corrections later on because if you ever want to make a change to how they are represented, you're stuck making the change to each copy of the group.

Template Properties

Template Properties (called Template Parameters) allow each template instance to reference different data. Because the primary use of templates are the ease of maintaining repeated user interface elements, correct use of Template Parameters is very important. This is very similar to the concept of Parameterized Popup Windows. In that case, any Custom property on the Root Container of the window is used as a parameter, and is passed into the window when it is opened. With Templates, you have a property in the root of the master template that is exposed when you drop a Template Instance on a window.

Indirection and UDT Tags

There are two primary ways to achieve indirection when using templates. Let's continue to use the example of a motor. Your system has many motors in it, and your template is used to display the status of the motors and control the motor's running mode. The goal is to be able to drop instances of the template onto your windows, and configure them in a single step to point to the correct motor's tags.

The Drop Target Parameter

When you specify parameters in the Custom Properties window (right-click the checkered-box of the template and select Customizers > Custom Properties), you can set one of the parameters as the Drop Target. This allows you to drop a Tag of that type onto your template instances or onto a window to facilitate even quicker binding. For example, let's say that you have a parameter that is an integer and you've made it the drop target. If you drop an integer tag onto a window, your template appears in the menu dropdown list of components which is displayed. Choosing your template creates a template instance and binds that parameter to the tag.

This also works for UDT tags. Lets say you have a custom data type called Motor and a template with a Motor-typed parameter set as the drop target. If you drop a motor tag onto a window, it creates an instance of your template automatically. If you have more than one template configured with Motor drop targets, you have to choose which template to use.

Global Templates

Global Templates work the same as any other Template with the added bonus that they are globally scoped and available to be used and edited across all Projects. This is useful for very generic Templates which will be used across multiple Projects. For Templates specific to a certain Project, it is still recommended that they be created in the Project Templates space, so that they are not accidentally modified in a Project that is not using them.

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