Theben KNX Series Handbook page 26

Object 25: External actual value
Only available if external actual value has been selected as a source.
Receives the room temperature from another measurement point via the bus.
This object can be activated on the actual value parameter page.
Object 26: Send actual value failure
Only available if the actual value monitoring is activated (Monitor actual value = yes).
Sends a 1, as soon as one of the selected sources for the actual value provides an unusable
value, or (if selected) if no new actual value telegram has been received by the external actual
value object within the actual value monitoring time.
Unusable temperature values might occur if a temperature sensor is mechanically damaged, or
if the electrical connection is interrupted or short-circuited.
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As long as at least one valid actual value remains available, this will be continued to be
used for control. This is the case if the average value is determined out of 2 or 3 sources.
Object 27: Receive outdoor temperature
Only available if the set point correction at high outdoor temperature parameter has been set to
calculate internally and send.
Receives the outdoor temperature for internal set point adjustment in cooling mode
Object 28: Receive dew point alarm
The object is available if the cooling function has been selected on the Settings parameter page
(control = heating and cooling).
When receiving a 1, cooling will be stopped, so the temperature cannot drop down to the dew
point.
RAMSES 718 P / RAMSES 718 S
The application programmes RAMSES 718 P/S
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