The Audio Voiceover architecture of Imagstore 750 is radically different from earlier Imagestore devices. The older StartVo/FinishVo script commands will control Voiceover 1, but not Voiceover 2. Here’s how to control the new voiceovers using PropertyLinks, and scripting.
Add an IS750 Icon to the panel

Drag the IS750 from the parts bin to the panel, and set the IP Address accordingly.
Add a button, and open the PropertyLink editor

Drag a button from the parts bin, and use the Property Inspector to locate the property called PropertyLink. Then, click on the “…” button to open the editor
Choose the required VoiceOver State property

You’ll need to drill down into the IS750 properties to locate the VoiceOvers and then the “state” property. Select it, then click OK when you’re done.
Change the button caption

When you set a PropertyLink for a button, a caption is automatically generated, but we’ll replace it with a shorter one,
Run the panel

Pressing the “Run Panel” button starts the panel. Because we’ve used a PropertyLink, the button will automatically follow the internal Voiceover state of the imagestore.
Controlling the voiceover from a script
Using classic Helm Scripting, you’d turn the voiceover on and off like this:
IS750_1:Set(Voiceover2In:State, true) IS750_1:Set(Voiceover2In:State, false)
Using Lua scripting, this gets translated to:
--lua helm.set("IS750_1","Voiceover2In:State", true) helm.set("IS750_1","Voiceover2In:State", false)
You can also read the current state from lua
if helm.get("IS750_1","Voiceover2In:State") then --vo is on else --vo is off end