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and establish upper and lower control limits. Five keypad entries define the operational
parameters. These parameters are: User Control Setpoint, Minimum User Setpoint,
Maximum User Setpoint, Low Input Value, and High Input Value. The low and high
input values describe the input transducer range. The control setpoint is the primary
operational parameter while the minimum and maximum setpoints describe the extents of
the desired operating range and provide secondary control as described below. The
allowable range for all of these parameters is –9999.99 - +9999.99.
The analog input and output are polarity sensitive and can be configured for different
types of inputs. See the Typical Wiring and Unit Controller Specification sections of this
manual for more information regarding the inputs and outputs.
The analog input must be connected to IN-2. This input
must
be configured for either of
two different types of input signals:
0-5Vdc: The output impedance must not exceed 10KΩ. The input impedance of
the controller is 1MΩ.
This input is polarity sensitive.
Be sure the connections
from the source are correctly polarized at the controller.
Thermistor: Precon type 2 (10k ohm at 77°F) Input voltages should range
between 0.489V and 3.825V. See the wiring diagrams for recirculating model
units for typical connections of transducers.
The IN-2 configuration jumpers on the controller must be set for the
appropriate input signal.
A contact closure between the appropriate terminals on the unit’s terminal strip
located in the unit’s main control panel will drive the output to 100%.
See the
Typical Wiring Schematic and Multiplexed Input sections of this manual for more
information.
Direct Acting
The controller output is modulated by a
PID
loop from 0% to 100% based on the User
Control setpoint and the input signal. As the input signal increases the output voltage
increases. Additionally, a secondary control acts to override the
PID
loop to scale the
output as follows.
If the input variable equals the User Control setpoint, the output will be determined by
the
PID
loop. In this situation the override has no effect on the output value.
If the input variable is above the User Control setpoint, the output
could
increase from
0% to 100% as the input variable increases from the User Control setpoint to the Max
User setpoint. In this situation the output value is the greater of the
PID
output or the
override output.
If the input variable is below the User Control setpoint, the output
could
decrease from
100% to 0% as the input variable decreases from the User Control setpoint to the Min
User setpoint. In this situation the output value is the lesser of the
PID
output or the
override output. See the following example.
