In an industrial environment, the smooth operation and ability to handle requests without problems is crucial to operation, so we must build robust code that allows for the unexpected and in doing so, the HMI becomes the central place that operators will go to to diagnose problems.
This is a companion discussion topic for the original entry at https://www.solisplc.com/tutorials/connecting-an-s7-plc-to-a-touch-hmi-and-configuring-plc-tags-and-data-structures