get the initial parameter values when the device is opened.

protocol/enttec/dmx-usb-pro/widget.cpp

@@ -88,8 +88,11 @@ void Widget::open()
 {
   if (getSerialNumber(500))                 // check for valid call/response from device
   {
+    {
       std::scoped_lock lock(mtx_metadata_);
       usb_mode_ = USBhost;                   // note connected state
+    }
+    getParameters(0, 500);                  // retrieve widget metadata
   }
 }