[DB600] General instruction manual
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6-8
2 Outputs
Set the control calculation method in MODE7 for the specification with 2 outputs.
6-8-1
PID control calculation
PID calculation is performed at the heating control and cooling control output sides individually.
Normally, the output 1 is used for heating operation (set "Control action (MODE6)" to "Heating control")
and the output 2 is used for cooling operation (set "Control action (MODE7)" to "Cooling control").
The gap between the setting value (SV) and 0% of output 2 (in the proportional band) is set to switch the
output between heating and cooling controls.
When the measured value (PV) is smaller than the setting value (SV), the output value from the heating
control side is used, and the output value from the cooling control side is used in the opposite condition.
Setting the gap creates a dead band for switching the output between heating and cooling controls and
also enables the heating output and cooling output at the same time.
Positive gap indicates the area where neither the heating nor cooling side produces output.
Negative gap indicates the area where both the heating and cooling sides produce output.
Heating output
Cooling output
The following is an example of setting the gap for output 2 when the deviation is zero (PV = SV).
- Setting condition -
Control action ·············································Output 1 "Heating control", output 2 "Cooling control"
Output preset ·············································Output 1 "50%", output 2 "0%"
When you want to have the cross shape shown in the below figure (50% output for both output 1 and 2),
the gap is obtained by the formula: G [%] = -P / 2.
* P: Proportional band of output 2
Output
Output 1
proportional
band
Output 2
proportional
band
Gap > 0
Gap < 0
Output 1
proportional band
Output 2
proportional
band
Output
Output 2 proportional band
Gap
