Watlow Series PD - Manual (Page 132)

W a t l o w S e r i e s P D
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C h a p t e r 1 0 F e a t u r e s
Autotuning
The autotuning feature allows the controller to
measure the system response to determine effective set-
tings for PID control. When autotuning is initiated the
controller reverts to on-off control. The temperature
must cross the Autotune Set Point four times to com-
plete the autotuning process. Once complete, the con-
troller controls at the normal set point, using the new
parameters.
To initiate an autotune, go to Device Configura-
tion > Control Loops > Loop 1 or 2 > Loop Settings
and click the Start Autotune button. During an auto-
tune, Control Loop Status indicates Autotuning. Once
the autotune is complete, Control Loop Status reverts
to its original status.
Inputs
INFOSENSE-P™ Temperature Sensing
Watlow’s INFOSENSE-P™ feature can improve
temperature sensing accuracy by 50%. Watlow’s INFO-
SENSE-P™ thermocouples and RTD temperature sen-
sors must be used together to achieve these results.
Each INFOSENSE-P™ plug and play “smart” sen-
sor provides sensor characterization information to the
Series PD. These values characterize Watlow sensors
resulting in greater system accuracy.
To set up an analog input to accept an INFOS-
ENSE-P™ sensor, go to Device Configuration > In-
puts > Analog Input 1 or 2 > Analog Input Sensor
Type and select InfoSense PnP.
The Series PD reads the INFOSENSE-P™ sensor
information upon power up and any time an input error
occurs. Contact your Watlow salesperson or Watlow au-
thorized distributor for the pricing and availability of
Watlow INFOSENSE-P™ sensor products.
Calibration Offset
Calibration offset allows a device to compensate for
an inaccurate sensor, lead resistance or other factors
that affect the input value. A positive offset increases
the input value, and a negative offset decreases the in-
put value.
To view or change the input offset value, go to De-
vice Configuration > Inputs > Analog Input 1 or 2
> Single Offset Value. Enter an offset value and click
the Submit button to send the new values.
Filter Time Constant
Filtering smoothes an input signal by applying a
first-order filter time constant to the signal. Filtering
the input signal may improve the performance of PID
control in a noisy or very dynamic system.
To view or change the filter time constant value, go
to Device Configuration > Inputs > Analog Input 1
or 2 > Input Filtering Filter Method and select
First Order. Enter a Filter Time Base value and
click the Submit button to send the new value.
Unfiltered Input Signal
Time
Temperature
Filtered Input Signal
Time
Temperature
Time
Temperature
Temperature Reading
from Sensor
Actual Process Temperature
Negative Calibration Offset will
compensate for the difference
between the Sensor Reading and
the Actual Temperature
Time
Temperature
Autotune begins
Process Set Point
Autotune Set Point
(90 percent of Process Set Point)
Autotune complete