Hach sc1000 - Manual (Page 82)

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Advanced Operations
PROPORTIONAL
Default value: 0
Sets the proportional part of the PID controller (in minutes).
The proportional part of the controller generates an output signal which is linearly dependent to
the control deviation. This part responds directly to any changes at the input but starts to
oscillate easily if set to high. The proportional part cannot completely compensate disturbances.
INTEGRAL
Default value: 0
Sets the integration part of the PID controller (in minutes).
The integral part of the controller generates an output signal which increases linearly when the
control deviation is constant. The integral part responds slower than the proportional part but can
completely adjust to disturbances. The higher the integral part value is set, the slower it
responds. If the integral part is set to a low value, it can start to oscillate.
DERIVATIVE
Default value: 0
Sets the derivative part of the PID controller (in minutes).
The derivative part of the PID controller gives an output signal. The faster the control deviation
changes, the higher the output signal gets.
Control deviation changes=Output signal.
Control deviation does not change=No output signal.
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.
SNAP SHOT
Displays the latest snap shot of the process value.
With the help of the output current the PID controller tries to approach the controlled process
value to the set point.
CURRENT
Displays the calculated output current (in mA).
By default the calculated output current does not represent the real output current. The real
current output depends on the opposite input resistance and can never exceed 22 mA.
LOG INTERVAL
Default value: OFF
Sets the interval (in minutes) for logging the displayed value into the data logger.
Options: OFF, 5min, 10min, 15min, 20min, 30min
VERSION Displays the software version number.
LOCATION Displays the current location.
SYSTEM SETUP
OUTPUT SETUP
mA OUTPUT INT/EXT