Desktop.DASH Web & Text Controls

November 2012

Until now we have created a project, configured a driver and added Display, Lamp and Image controls to the dashboard.

Home Desktop.DASH Previous Page Desktop.DASH Add Indicators

Next we can look at the other READ only controls, Web and Text, which have very similar properties and methods.

Web Control (Experimental!)

The Web control has the ability to either display a single external web page, that is a web page outside of the current domain, like a weather site, or perhaps a page that contains useful telemetry or web cam images, etc. Importantly, the actual control itself has known limitations, and by design therefore, all links within an external web page are disabled.

Alternatively the Web control can select from a range of locally stored web pages to display, the displayed page being based upon the value of a PLC data store. The intention being that targeted information with formatted text and images could be displayed either in response to maintenance or alarm conditions, or even for sequential process instructions.

Add a new Web control from the dashboard menu... and select it's set up properties...

New Empty Web Control

Web Control Properties Setup

As usual you can enter a meaningful UserLabel, eg "Weather Forecast", and optionally, for a dynamic web page loader, an associated DataPoint to map to.

As discussed you have 2 methods with this control:-

• 1. STATIC - where the web page can be local or pulled in from the Internet

  2. DYNAMIC - where the value of a DataPoint determines the page to be loaded, which must be a local HTML type file (that is a file found in the project folder.)

Important Notes

It is strongly recommended that you only include ONE Web control in your dashboard - as they can be a huge drain on resources when loading Internet content.

Externally referenced URL's must be reasonably qualified, eg http://www.forecast.co.uk/south-west-england/ or www.bbc.co.uk.

Locally referenced web pages must exclude any URL qualification, so HowToResetFireAlarm.html is sufficient, and must include the .HTML extension.

Place the HTML files in the project folder. DO NOT use relative paths or the like, and ensure that any content, eg images, are also in the project folder.

The mechanism for determining what dynamic page to load from the local project folder uses simple <, > type operators (exampled further on.)

Static External Web Page Example

Static External Website URL

Note

The page will not load until Desktop.DASH enters either Demo or Run mode

External Web Page Loaded

Dynamic Local Web Page Example

The statement system for selecting the local resource file is as follows:-

<x resource1.ext

x resource2.ext

>x resource3.ext

Example. If the DataPoint value is less than x then resource1.ext will be loaded, if the value = x the resource2.ext will be loaded and if the value > x then resource3.ext will be loaded.

Resource Switching Calculation

If you hadn't created any resource file or placed it into the project folder then you will get an error...

Error Message

The only available operators are <, > and "value is equal to". (DO NOT actually use the = sign, it's implied.)

You can have multiple statements as required, and the one that most matches the situation will be selected, for example...

<50 ExtraLowTemp.html

<100 LowTemp.html

100 NormalTemp.html

140 PerfectTemp.html

>100 AboveTemp.html

>180 HighTempAlarm.html

If the value was 99 then LowTemp.html would be selected for display.

Notes

You must only add one statement per line, or an error will result.

Do not use any other operators.

You need to carefully ensure that your statements encompass all possible values, eg if you do not have <100 resource.ext, and your value falls below 100 it will go off the scale and no local resource will be loaded.

Other error messages will be displayed should they be required when the Web control is running.

Text Control

The Text control operates as the Web control. You can utilize either a single static text, or map multiple text statements that are displayed according to the value of an associated DataPoint, using the example described above. However, you can ONLY display text, not any other form of resource.

Example.

<1 All Ok

1 Heating System Fault

2 Air Conditioner Fault

3 Fire Alarm Fault

>3 Call Security Now!

A value of 2 will result in "Heating System Fault" being display.

In the next section we'll look at the WRITE-able controls, namely Slider and Button, and the license installation requirements.

Desktop.DASH Slider, Button & Licenses