HS/FS Backup "telegram response" in case of HS, IP-network or other fancy device failure?

[McKajVah]

Hi.

I'm a bit concerned with Homeserver, KNX-Router, Switch (IP), future "Internet of Things" devices stability and would like to have a "fail-safe" of only internal KNX-bus components without any interaction from the HS or other fancy components. The reason being I'm often 2-3 weeks away from home with wife and kids home alone and needs basic operation in case the Homeserver, IP-network goes down.

Is there a good way to program this? Any thoughts?


One simple example:

I have 3 temp measurements in a room (floor, switch and ceiling) and normally the HS4 calculates an average of the 3 and "sends" it to the heating actuator. If HS goes offline, I want the heating actuator to listen and respond to the switch temp reading. (see attached picture).

You can answer in German as I'll use Google translate...

Regards.
Kaj

[bramlangen]

It you worry about the failure of extraneous systems, then configure all of your critical functions within the bus components (actors, sensors, etc.), and only have the 'nice to have' functions in the HS. One way to eliminate the risk of the network failure is to have your HS directly connected to the bus using the RS-232 connection.

In the example you show you could configure the sensor and actor to always use the sensor value as input. That way, as long as the bus and these two components function, the device will be controlled. You can then let the HS listen for any change to GA 1.1.5, immediately do the calculation, and send the result to the actor. It is not a highly elegant way of doing this, as the actor will see two updates in quick succession, but it would achieve what you are after.

Bram