This logic group determines, for example, the setpoint temperature of an air conditioner depending on the outside temperature and then sends it cyclically to the output.
To the function.
- Up to an outdoor temperature of 23°C, the setpoint specified by the user is adopted one-to-one and output cyclically.
- From an outdoor temperature of 23°C, instead of the specified setpoint, 6°C is first subtracted from the current outdoor temperature and this is then output cyclically.
The two value storage elements have a central function. They always hold the setpoints for both cases. The setpoints for the two value memories come:
a) Via the "Setpoint temp. air-conditioning" input.
This value is specified by the user and transferred directly to the value memory "Value > 23°C".
b) via the "Outdoor temperature" input.
Here, each received telegram value is reduced by 6 and transferred to the value memory "Value <23°C".
The following comparator element is triggered after each subtraction. The outdoor temperature is compared with the fixed value 23.
The corresponding value memory is then triggered by the result (TRUE/FALSE) of the comparator.
To ensure that only one value memory can trigger at a time, filters are configured for the TRIG inputs and thus only trigger at the appropriate result.
As a last step, one of the two value memories transfers the setpoint to the cyclic transmitter, which then cyclically sends the setpoint to the output every 10 seconds.
In this logic group, it must still be taken into account that the setpoint temperature must also be changeable when the outside temperature is below 23°C!
This is necessary because the value memory only transfers the setpoint to the cyclical transmitter when the comparator triggers! For this reason, an "additional trigger" is necessary.
This additional trigger is a gate element that is (co-)activated by the comparator.
In this way, when a new setpoint temperature is received, it is transferred to the value memory "Value > 23°C" and the trigger input of the value memory is triggered in parallel via the gate element. In this way, the new setpoint temperature is accepted for the output.
In the event that the outside temperature is above 23°C, the door element is deactivated and the new setpoint temperature is only written to the value memory.