DLproc: Control Program for the DL 2314 Unit (Process Control & Transducers)
 PID/ON-OFF Controller Window

This window gives the control panel for the PID/ON-OFF Controller when the PC is used to regulate the processes (level, temperature, ..) of the DL 2314 Unit.
The window looks like in the figure.

NOTE: all the magnitudes inside the controller are indicated and can be changed in percent (%).

In the window there are:

Mode Section:
contains the commands to change the controller operating mode. Only two commands can be active at the same time:
PID controller and Manual
ON-OFF controller and Manual

The Manual command is used to stop the regulation of the controller  and to put it in the manual mode. In this mode the output can be changed manually using the slider Out.
Sliders Out, Var and SP:
The Var slider (red) indicates the value of the variable (the controlled signal).
The SP slider (green) indicates the value of the set point selected with the controls on the System Diagram Window. The set point can also be changed inside the controller with the SP slider if the Disable Ext. Set Point control is active. 
The Out slider indicates the value of the output of the controller, calculated by the controller according to the values of the set point, the variable and the regulation parameters (proportional, integral, derivative, hysteresis). The output value can be changed manually using the Out slider if the controller is in the Manual mode.
Set Point, Variable, Output indicators:
indicate the numerical values, in percent, of the Set Point, the Variable and the Output.
ON-OFF Par. Section:
contains the parameters of the ON-OFF regulation.
In this regulation it is possible to change the value of the Hysteresis, in percent of the actual set point, between 0 and 50%. The controller calculates the percent difference between the Set Point and the Variable, and compare this value with the hysteresis to compute the state of the output.
PID Parameters Section:
contains the parameters of the PID regulation.
Gain.
It is the gain value. I.e. the value used to multiply the error (Set Point - Variable) to calculate the Output. If the Set Point is 50% and the variable is 46%, then with a Gain=1 the value of the output is 4%, while with Gain=10 the output is 40%.
Integr.
This is the number of times per minute that the normal output calculated based on the Gain is reapplied to the output. This setting affects the ability of the controller to correct for a continuous offset between the Set Point and measured value (Variable). The maximum value is 60 (every second).
Deriv.
This value determines how many minutes the controller "looks ahead" to determine how the output should be adjusted. The calculation is done by extrapolating from the previous measured value to determine what the value will be at the specified lead time. This setting affects the ability of the controller to respond ahead of time to rapid changes in the measured value (Variable). The minimum value is 0.02 (about 1s).
Disable Ext. Set Points Command:
permits to disable the Set Points on the System Diagram Window and to enable the controller SP slider, to modify the Set Point directly inside the controller.
Action Section:
contains the commands to stop, restart and reset the PID controller.
These commands are:
Stop: stops the PID controller. When stop is active the Output is not computed by the controller but can be changed manually with the Out slider.
Run: starts the PID controller. When run is active the output is calculated by the controller according to the values of the set point, the variable, and the regulator parameters.
Reset: initializes the controller with its internal starting parameters. Use this command when the controller loses the control of the system (Press first of all Reset, to initialize, and then Run to restart).
OPmode Section:
contains the commands to set the regulation action as Normal (direct) or Reverse. The Reverse regulation inverts the sign of the output signal.