Why Doesn't My ActiveX Object Update in a Remote Panel?

Updated Oct 14, 2019

Reported In

Software

  • LabVIEW

Issue Details

I have an ActiveX control on my Remote Front Panel, but it doesn't update with my LabVIEW code. How can I solve this?

Solution

It is not possible to update ActiveX object in LabVIEW Remote Front Panel.

An instance of an ActiveX object on the LabVIEW front panel is controlled by the ActiveX server interface. When you create a Remote Front Panel by publishing your front panel to a web page, a new instance of the object is created on the Remote Front Panel. The instance of the front panel and the instance of the Remote Front Panel is not related so that you can't control the ActiveX object in Remote Front Panel by controlling LabVIEW controls.

Additional Information

When you place an ActiveX object on your LabVIEW front panel, it is embedded in an ActiveX container. When you first use the ActiveX object, an instance of the object is created within the container. LabVIEW, through the object's specific ActiveX server interface, has the ability to control that instance's properties. Using Windows Media Player as an example, LabVIEW can control playing and pausing a movie but it is actually the Windows Media Player ActiveX server which is responsible for playing and displaying the movie.

When you create a Remote Front Panel by publishing your front panel to a web page, the ActiveX containers are also published. The difference is that a NEW instance of the object is created on the remote computer. This means that this specific object is unrelated to the ActiveX object that is in the LabVIEW front panel, and is controlled using the ActiveX server on the remote machine. Therefore, when you attempt to control this ActiveX object using LabVIEW controls, it is only going to control the instance of the object in the LabVIEW front panel, not the Remote Front Panel. For this reason, you will notice that another functionality is unavailable on the Remote Front Panel. When you right click on the Windows Media Player Control in the LabVIEW front panel, a short cut menu pops up that allows you to play the movie, view it as a full screen, etc. If you try this on the Windows Media Player Control on the Remote Front Panel, you will still see the short cut menu, but most of the options will be disabled.

This behavior is due to the nature of embedding ActiveX objects in different applications, including a remote front panel window, and occurs because the LabVIEW front panel is not simply transmitting screenshots to the remote front panel which updates its screen.

The attached example VI has a Windows Media Player and an ActiveX calendar on the front panel. Using Remote Front Panels, you will see the behavior described above.