The Siemens Industry Automation Division has improved the performance and equipment of its portable devices for wireless operator control and monitoring of machinery and plants, as well as enhancing them with additional functions. For safety-oriented applications, the Mobile Panel 277F IWLAN communicates via a "Rapid Roaming" process in order to ensure interruption-free transmission of the wireless signals. Optimization measures in the Mobile Panel 277 IWLAN and Mobile Panel 277F IWLAN for safety-related applications include color display of the WLAN signal strength with an additional vibration alarm, which is triggered when a specific lower limit threshold is violated. Handling of the enabling button has also been improved.