adccommunitymod (AutomationDirect) asked a question.
Cycling a heater
Created Date: November 25,2014
Created By: GaryRice
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I 've set up a program via an ezTouch panel to a DL06 that turns a heater on and off using a button on the touch screen. I would like to now cycle the heater such that it maintains a set temperature. But I want to do that without affecting the state of the touch panel switch. That is, if the switch on the panel shows the heater as "ON ", the button should remain "ON " even though the heater may actually be off (at its set temperature). Suggestions please. Gary
Created Date: November 25,2014
Created by: scott.lawrence
use the PID in the DL06 to control the heater in an on/off configuration
Created Date: November 25,2014
Created by: bcarlton
I take it that you want the HMI to display the state of 'controlling the temperature ' rather than 'is the heater on right now '.
Just point it to any 'enabling ' bit for the process in your PLC.
Created Date: November 26,2014
Created by: GaryRice
I read the chapter on the PID stuff. But there is too much calculus for me to successfully implement a PID loop.
However the "enabling bit " seems less daunting. I'm reasonably new at ladder programming.
What is an "enabling bit "?
Gary
Created Date: November 26,2014
Created by: GaryRice
v1000>v1100 ------ out(heater)
I used this approach as my first attempt. The heater cycled correctly but it had the undesirable effect of turning the touch screen button off as well when the heater turned off.
I want the operator to control the heater (or at least have that appearance). So the button MUST stay on even when the heater is cycling. Only the operator should be able to turn the button off.
Gary
Created Date: November 26,2014
Created by: scott.lawrence
use a bit to enable the heater logic via a pushbutton on the HMI
point the status indicator the the enable bit
in the logic, use the comparison statement to turn the heater on/off (personally, I use two comparison statements, like a high/low setting, and a timer to prevent output chattering)
Created Date: November 25,2014
Created by: GaryRice
I 've set up a program via an ezTouch panel to a DL06 that turns a heater on and off using a button on the touch screen.
I would like to now cycle the heater such that it maintains a set temperature. But I want to do that without affecting the state of the touch panel switch.
That is, if the switch on the panel shows the heater as "ON ", the button should remain "ON " even though the heater may actually be off (at its set temperature).
Suggestions please.
Gary