It might work with NULL instead of UNDEF.
You could use a proxy Item and a Rule instead of the Group to keep track of whether a sensor is offline or reporting a bad value or something. But over all I suspect you can’t do this with just a Group.
It might work with NULL instead of UNDEF.
You could use a proxy Item and a Rule instead of the Group to keep track of whether a sensor is offline or reporting a bad value or something. But over all I suspect you can’t do this with just a Group.