Example 2 - Duplex Control - Pid With Heat/Cool (Duplex) Output - Honeywell UMC800 Reference Manual

Function Blocks
2.50 PID Function Block,

2.50.2 Example 2 - Duplex Control - PID with Heat/Cool (Duplex) Output

Use standard PID Function Block
• Select PID A Duplex or PID B Duplex
• Set to Reverse acting
• Use Tuning Constant Set #1 from 50% to 100% Heat Output
• Use Tuning Constant Set #2 from 50 % to 0% Cool Output
Choose Output Types for Heat and Cool (Current/Current, Current/Time
Proportioning, Time Prop./ Time Prop., etc.), connect each to PID block output.
Use output block scaling to set duplex output spans. Set output scaling Range Lo
and Hi to 50 - 100 % for heat output and 50% to 0% for cooling output,
respectively. You may need to adjust range limits for overlap or deadband as
required.
(4 mA)
0%
100%
Output
50%
( %)
0%
0%
154
continued
(20 mA)
100%
Output 1 HEAT
Reverse acting
control
Direct acting
control
Output 2 COOL
100%
Figure 2-48 Duplex Control Example
Function Block Reference Guide
Heat
Output
Hi - 100%
Hi - 0 %
Lo - 50%
Lo - 50%
Or,
Time
Proportioning
Cool
Output
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