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Iii-16.12 setpoint functions 260, Setpoint / setpoint cascade 260, W2 - safety setpoint 260 – West Control Solutions KS98-1 User Manual

Page 260: Setpoint functions 260 - 264, General 260, Terminology 260, Iii-16.12 setpoint functions, X - w

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III-16.12

Setpoint functions

Terminology

w

internal setpoint

we

external setpoint

w2

second (internal) setpoint

Weff

effective setpoint

xw

control deviation (x-w r process value - )

General

Several possible setpoints are available. For the priorities, see the
drawing shown opposite. "Safety setpoint " w2 is given priority
over the other setpoints. Switchover between setpoints is possible
via interface or via the digital inputs of the conroller block.

If gradient control was activated, a change will be made effective
continuously instead of being made effective by a step r gra-
dient control page 261.

By activating digital input

w stop , the instantaneously effec-

tive setpoint is maintained. In this case, neither a setpoint change
nor switchover to another setpoint becomes effective.

Setpoint / setpoint / cascade

Configuration word

WFunc can be used to select, if switch-over to the external setpoint (setpoint / cascade) is also

possible in addition to the internal setpoint.

Setpoint

(

WFunc =

Setpoint) Setpoint control means that the setpoint is firmly predefined by the internal setpoint W.

Setpoint/cascade

(

WFunc = Fest/Folg) Setpoint /cascade control permits switchover between internal setpoint

W and external

setpoint

We . Switchover is via digital input we/wi or via the interface.

Unless this input is connected, or if a 0 signal is applied, the external setpoint is used as effective setpoint. Unless di -
gital input

we/wi as well as analog input wext are connected, the controller invariably uses the internal setpoint.

W2 - safety setpoint

The second setpoint W2 can be activated at any time and has highest priority. The change-over between internal set -
point and W2 can be triggered via interface or the digital control input

w/w2. In order to make the W2 effective, on

w/w2 is a logic 1 to be attached. If the internal setpoint is to be active, a logic 0 must be given on we/wi.
In the past

W2 was designated as "safety setpoint". Whether W2 takes over safety functions or only a pre-defined

starting position in certain process conditions, becomes determined only by the kind of the use and integration into an
automation concept.

9499-040-82711

III-260

Setpoint functions

x - w

+

-

Weff

W2

xeff

w/w2

we/wi

w

Wext

Fig. 77