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PRESYS
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Instruments
as output 2. Note that in this form of control, it is the ON time of the output device that
varies according to PID output computation. The device ON/OFF period being
constant and defined by the user at level 3 of the Output Configuration (RELAY), it is
the duty cycle that actually varies.
The adjustable parameter ranges shown on figure 20 are given below.
Mnemonic
Parameter
RATE
Rate
BIAS
Offset
HYST
Hysteresis
GAIN
Gain
RSTN
Manual reset
INT
Integrative rate.
DER
Derivative time
3.2.6 - Level 6 - Tune
The DCY-2057 Controller can apply PID control algorithms both for control
loop 1 and for control loop 2. The PID parameters: Gain (GAIN), Integrative Rate
(INT) and Derivative Time (DER) are adjustable over a wide span of values in order
to accommodate several processes with varying characteristics. In the event of a
specific control application, these parameters should be adjusted in order to achieve
the best system performance.
For this purpose, the DCY-2057 Controller is provided with auto-tune
algorithms which, whenever activated by the user, will automatically compute, both
on start-up (the controlled variable is far from the setpoint, as is usually the case
when the instrument is switched on) and on demand (the controlled variable is close t
the setpoint, as is usually the case when the system already under operational
regime), the optimum PID values based on process reaction curve during the auto-
tune cycle. After carrying out PID computation via the auto-tune algorithm the
Controllers start controlling the process in the automatic mode under those new
values.
The auto-tune algorithm is only carried out provided:
i) the control is of the DUAL type.
ii) the control algorithm for loop 1 or loop 2 is selected for PID.
iii) the programmable setpoint is not enabled; STATE should be switched off.
DCY - 2057 Pressure Controller
Adjustable
span
0.01 to 99.99
-999 to 9999
-999 to 9999
0.01 to 99.99
0 to 99.99
0 to 99.99
0 to 99.99
Factory
Units
Value
1
------------
0
EU
0
EU
1
-------------
50.0
%
0
rep/min
0
min
Maintenance
Page 41
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