Function Set To Pwm Control/Pid Control Working Mode - Hach sc1000 User Manual

Advanced Operations

6.3.3.7 Function set to PWM CONTROL/PID CONTROL working mode

PWM CONTROL/PID CONTROL
SET FUNCTION
LINEAR
PID CONTROL
SET TRANSFER
SET MODE
AUTOMATIC
MANUAL
MANUAL OUTPUT
–
(0% 100%)
PHASE
MINIMUM
–
(0% 100%)
MAXIMUM
–
(0% 100%)
SET POINT
DEAD ZONE
–
PERIOD (0 600 s)
PROPORTIONAL
INTEGRAL
DERIVATIVE
102
Default value: LINEAR
The 2nd SET FUNCTION menu sets the PWM signal status.
Signal is linearly dependent on the process value.
Signal works as a PID controller.
Default value: 0%
Sets a substitute PWM ratio when some error conditions are detected in the selected source or if
the source is missing.
Default value: AUTOMATIC
The relay output works as a PID controller.
The relay output has got an on/off ratio as set in the menu MANUAL OUTPUT.
Indicates the current on/off ratio.
Additionally the on/off ratio can be set (condition: SET MODE is set to MANUAL). Note that this
ratio cannot exceed a value beyond the values set in the MINIMUM and MAXIMUM menus.
Default value: DIRECT
Reverses the leading sign of the control deviation for the PID controller.
Default value: 0%
Sets the minimum PWM ratio.
Default value: 100%
Sets the maximum PWM.
Default value: 10
Sets the process value which is controlled by the PID controller.
Default value: 1
The dead zone is a band around the set point. In this band the PID controller does not change
the PWM on/off ratio output signal. This band is determined as set point +/- dead zone. The
dead zone stabilizes the PID controlled system which have a tendency to oscillate.
Default value: 5 seconds
Sets the cycle duration of the PWM output signal.
Default value: 1
Sets the proportional part of the PID controller.
The proportional part of the controller generates an output signal which is linearly dependent to
the control deviation. The proportional part reacts on any changes at the input but starts to
oscillate easily if the value is set high. The proportional part cannot completely compensate
disturbances.
Default value: 15 minutes
Sets the integration part of the PID controller.
The integration part of the controller generates an output signal. The output signal increases
linearly if the control deviation is constant. The integration part responds slower than the
proportional part and can completely compensate disturbances. The higher the integration part,
the slower it responds. If the integration part is set to low, it starts to oscillate.
Default value: 5 minutes
Sets the derivative part of the PID controller.
The derivative part of the PID controller generates an output signal which depends on the control
deviation changes. The faster the control deviation changes, the higher the output signal gets.
The derivative part creates an output signal as long as the control deviation changes. If the
control deviation is constant, no signal is created.
The derivative part is able to smoothen the oscillation caused by the proportional part. The
derivative part allows the proportional part to be set higher and the controller responds faster.
If there is no knowledge about the controlled process behavior, it is recommended to set this part
to "0", because this part tends to oscillate strongly.