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LOGO! functions
4.4 Special functions list - SF
Functional description
If the input A/M is set to 0, then the special function issues output AQ with the value that you
set with parameter Mq.
If the input A/M is set to 1, then automatic mode commences. As an integral sum the value
Mq is adopted, the controller function begins the calculations.
Note
For further information on the controller basics, please refer to the online help for LOGO!Soft
Comfort.
The updated value PV is used to calculate in the formulas:
Updated value PV
● If the updated value PV = SP, then the special function does not change the value of AQ.
● Dir = upwards (+) (timing diagram numbers 1. and 3.)
– If the updated value PV > SP, then the special function reduces the value of AQ.
– If the updated value PV < SP, then the special function increases the value of AQ.
● Dir = downwards (-) (timing diagram number 2.)
– If the updated value PV > SP, then the special function increases the value of AQ.
– If the updated value PV < SP, then the special function reduces the value of AQ.
With a disturbance, AQ continues to increase / decrease until the updated value PV again
corresponds to SP. The speed with which AQ changes depends on the parameters KC and
TI.
If the input PV exceeds the parameter Max, then the updated value PV is set to the value of
Max. If the PV falls short of the parameter Min, then the updated value PV is set to the value
of Min.
If the input R is set to 1, then the AQ output is reset. As long as R is set, the input A/M is
disabled.
Sampling time
The sampling time is fixed at 500 ms.
Parameter sets
For more information and application examples with application-related parameter sets for
KC, TI and Dir refer to the online help for LOGO!Soft Comfort.
204
= (PV • gain) + offset
Manual, 10/2017, A5E01248535-AA
LOGO!

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