If you haven’t yet, it would be useful to go through the Beginner’s Tutorial and the Concepts section of docs. These but attempt to explain the relationships between all these parts.
Things represent devices (or end points such as weather from a sure like Wunderground).
Things have Channels. Each Channel represents a single piece of information provided by that Thing (e.g. temperature) or something you can cause that Thing to do (e.g. turn on or off).
Items are the model of your home automation. Everything in OH works off of Items. It is the Items layer where Zwave Node3 Channel Switch gets mapped to LivingroomLamp. Rules, sitemaps, persistence, et al do not and should not care what technology the Item is linked to. All it cares about is there is a Switch that represents the lamp in the living room.
Items get linked to Channels. This is how the model (i.e. Items) get connected to the physical devices. If a Channel is a sensor reading, when the device reports a new value, the Item linked to that Channel gets updated with the new value. When you send a command to an Item linked to a Channel that controls the device, the command to the Item gets transmitted to the device.
There is a known bug right now that has been reported. Does this only appear when the file is loaded? If so it can be safely ignored for now.
That is very odd behavior I’ve not seen reported. Send like it should be all or nothing. It certainly looks like a bug.
That could be related. Do you see anything in openhab.log when you see this?
