User manual - ATR171 21
•
t m r.i .
: start / stop of Timer function (See par. 8.10);
The parameter 70
op.mo.
, enable other functions to use digital imput:
•
p r. cy .
: Pre-programmed cycle (See par. 8.7);
•
2t.s.
,
2t. s .i
,
3 t. s .i
,
4 t. s .i
: It’s possible to use digital input for setpoint change
function. This mode allows to recall 2 to 4 thresholds / setpoints by external
button without pressing the arrow keys during operation. The setpoints can be
entered during operation pressing SET key.
8.12 Heating-Cooling P.I.D.
ATR171 is suitable also for also for applications requiring a combined heating-coo-
ling P.I.D. action.
Command output has to be configured as heating P.I.D. (
Act.t.
=
heat
and
p . b .
greater than 0), and one of alarms (
a L. 1
,
a L. 2
or
a L. 3
) has to be configured as
cooL
.
Command output must be connected to actuator responsible for heating action,
while alarm will control the cooling action.
Parameters to configure for Heating P.I.D. are:
Act.t.
=
heat
Command output action type (Heating);
p. b .
: Proportional band Heating;
t.i .
: Integral time Heating and cooling;
t. d .
: Derivative time Heating and cooling;
t. c.
: Cycle time Heating.
Configuration parameters for Cooling P.I.D. are (example: action associated to alarm 1):
aL. 1
=
co oL
Alarm 1 selection (Cooling);
p.b.m.
: Proportional band multiplier;
ou.d.b.
: Overlapping / dead band;
co.t.c.
: Cycle time Cooling.
Parameter
p.b.m.
(that ranges from 1.00 to 5.00) sets the proportional band for
cooling action, according to the formula here below:
Proportional band for cooling action =
p. b .
x
p.b.m.
.
In this way it is possible to have a proportional band for cooling action that will be
equal to heating proportional band if
p.b.m.
= 1.00, or 5 times greater if
p.b.m.
= 5.00.
Integral time and derivative time are the same for both actions.
Parameter
ou.d.b.
sets the percentage overlapping between the two actions. For
installations where heating and cooling output cannot be activated at the same
time, a dead band will be configured (
ou.d.b.
≤ 0), vice versa an overlapping will be
configured (
ou.d.b.
> 0). Figure here below shows an example of double action P.I.D.
(heating-cooling) with
t.i .
= 0 and
t. d .
= 0.
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