Imagine there's a room full of people from Sweden, and they're all talking to each other in Swedish. Even though you can hear what they're saying, it doesn't mean anything to you because you don't speak Swedish. If you had the ability to speak Swedish, you would understand exactly what was going on.
Now imagine there's a network full of devices and a controller that all speak Z-Wave. Sensors are reporting temperature and humidity at regular intervals to the controller. But, even though you can hear what they're saying, it doesn't mean anything to you because you don't speak Z-Wave.
OpenZWave is a library that enables you to understand and speak Z-Wave. You can use it to create software that listens to the conversations, decides what action to take and even barks out orders in Z-Wave to devices (e.g., motion detection -> call the police). OpenZWave comes with sample applications that show you how to construct your own home automation software using the OpenZWave library. You can also use a software package such as Domoticz, HomeSeer, OpenHAB or SmartThings. These applications provide a broad set of home automation features and functionality so you don't have to program them yourself.
To use the least amount of battery, a device such as the ST814 spends most of its time sleeping. At user-defined regular intervals (for example, every hour), the device wakes up, reports the temperature and humidity to the controller and checks to make sure there are no other commands or requests waiting for it. Then it goes back to sleep. You determine how often the device wakes up and can set it according to the instructions you referenced.
If you want to intercept the temperature and humidity report from the ST814 to the controller and output it to the console with OpenZwave, you need to write some code or use someone else's program. The latter is easier, but might not enable you to do exactly what you want to do. Using OpenZWave is harder, but provides the capability to do just about anything you want to do.
