adccommunitymod (AutomationDirect) asked a question.
Created Date: July 04,2012
Created By: sshneider
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I am using the P3K to control process Temperature using BOTH a Chiller AND a Heater. The PID Instruction in the P3K is great but, it will only control 1 output and for a guy like me wanting to control 2 devices with 1 PID instruction, I'm kinda out of luck. Yes, there are other ways of programming around this (and I am having to use them) but, it just seems weird to me that something as powerful as the P3K doesn't have the same basic functionality that an AD $100 SOLO temp controller has. It sure would be nice if the existing PID Instruction could be "tweaked " or a new special Heating/Cooling PID instruction was released. As always, thanks for your consideration.
Created Date: July 05,2012
Created by: JDemsey
PID Split range
We usually do this by splitting the range so that say from 0-45% (reverse acting so the heater is on with 0% being full on and 45% full off). The cooling ranges from 55% to 100% direct acting. The 45% to 55% forces a deadband so heat and cool are not on at the same time, but those can be overlapped if needed.
This also allows either the heat output and/or the cooling output to be decoupled from the loop when another process variable requires a different sequence. For instance you normally control to dry bulb temperature but de-humidification requires reheating after sub-cooling the air to control to temperature and RH.
Created Date: July 07,2012
Created by: sshneider
Very Cool suggestion! Thanks!
Created Date: July 04,2012
Created by: sshneider
I am using the P3K to control process Temperature using BOTH a Chiller AND a Heater. The PID Instruction in the P3K is great but, it will only control 1 output and for a guy like me wanting to control 2 devices with 1 PID instruction, I'm kinda out of luck.
Yes, there are other ways of programming around this (and I am having to use them) but, it just seems weird to me that something as powerful as the P3K doesn't have the same basic functionality that an AD $100 SOLO temp controller has.
It sure would be nice if the existing PID Instruction could be "tweaked " or a new special Heating/Cooling PID instruction was released.
As always, thanks for your consideration.