8.3. Step-by-step control
The controller’s step-by-step control algorithm without feedback was
changed.
The description is provided below.
The controller offers two algorithms of the step-by-step control
for cylinder control:
• with no feedback signal from the valve – opening and closing of the
valve is based on PID parameters and control deviation,
• with a feedback signal from the valve positioning device – opening
and closing of the valve is based on PID parameters, control devia-
tion and valve position read from the additional input.
To select a step-by-step control, set one of the outputs out1...out4
to Y0p and one of the outputs out1…out4 to YCl. For the algo-
rithm with no feedback - the parameter fdb should be set to no,
for the algorithm with a feedback - the parameter fdb should be
set to yes. Additionally, set the insensitivity range for the set point,
in which the valve does not change its position - the parameter Hn
and select the set of PID parameters. Auto-tuning algorithm is not
available for the step-by-step control.
For the algorithm with feedback signal the parameter
i#flis available,
that specifies the state of the valve when the feedback signal error
on the secondary auxiliary input.
Step-by-step control with no feedback additionally requires the parame-
ters settings: valve open time tMuo, valve close time tMuc, minimum
valve work time mNTu.
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