adccommunitymod (AutomationDirect) asked a question.
Created Date: September 09,2013
Created By: JimG
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I have a 15 " C-more panel for a dryer system running on Allen-Bradley ControlLogix. On my main screen, I have a START dryer pushbutton and a STOP dryer pushbutton. The logic uses these as a standard start-stop configuration to enable the dryer. I got called in one night recently because the operators were trying to stop the dryer and as soon as they released the stop button on the panel (Set up as a momentary pushbutton), the dryer would start back up on its own. The START pushbutton (also configured as a momentary pushbutton) remained in the "touched " state. This was confirmed when I looked into the Contrologix program. This bit remained in a true condition regardless of whether the button was pushed or not. I stopped the dryer by toggling the bit in the program. After everything was stopped, I tested the start button several times and it worked as normal and has been working normal to date. I contacted AD Tech support and was told to check the tag name for the pushbutton and make sure it matched the program. OK. Then they said delete the object and recreate it and inport the tag name from the A-B database. OK. I'm not convinced that this was the cause of the problem. Tech support said it probably was not the panel. They had never heard of this situation before. Anyone else experience this issue?
Created Date: September 09,2013
Created by: scott.lawrence
not on a 15 ", but on an 8 " recently....
Fault Reset PB (momentary) on an 8 " HMI would not 'reset '. This button is set to be displayed only when the fault is on. Pressing the button on the HMI didn't show the visual (color) change of the OFF/ON state of the button.
Had to cycle the power to the HMI to get it to start working correctly. It's happened twice last week, but not since then...
and before anyone asks, the HMI & PLC both have the latest firmware, and connection is via ethernet.
Created Date: September 11,2013
Created by: mwdkmpr
I have had something similar to this happen in the past. I had a momentary PB in the HMI that would cause the PLC program to jump from a stage. Sometimes the PLC would jump from the stage before the HMI would send the off transition of the PB.
Created Date: September 11,2013
Created by: bcarlton
I have found that if the ultimate effect of a momentary button is to initiate a change in the PLC which causes a visibility or screen change on the HMI then I use the trailing edge of the button to perform the action in the PLC.
Created Date: September 11,2013
Created by: Do-more PE
The way that a momentary pushbutton works is that the HMI must send a request to the PLC for the button to turn on and another request for it to turn off.
If either of these requests fails to make it to the PLC, then unexpected results occur.
The better way is to use a set on and have the PLC reset it after the action is complete.
Created Date: February 05,2016
Created by: Bolatov27
Same Issue here i made changes in the PLC not in the CMore Panel EA7-T8C they reported they couldnt stop the machine... bit latched... in the HMI is momentary...
Created Date: March 20,2016
Created by: MikeMc
CMore Button Issues
Been there, done that.
The engineer is correct that the correct way is to set the bit in CMore and let the program reset it.
Here is the catcher, if it is something like start/stop or open/close these command must originate from the CMore. Problem is communications between the CMore and the controller. If the CMore cannot send the command to the PLC for some reason (usually I have found it caused by using a HMI and a SCADA system on the same PLC) the Cmore command will not get executed.
I don't think that the CMore tries to repeat the write if it fails or if it does, it may only try one time. In POV you have a read before write and read after write to have the operation verified on the panel. I also use a button with an indicator feature so the indicator is using the same point in the PLC as the command is using. That way the button will show if the command executed and will show if the command was executed by another system such as SCADA
Mike McClanahan
Global Production Solutions
Senior Automation Engineer
Created Date: September 09,2013
Created by: JimG
I have a 15 " C-more panel for a dryer system running on Allen-Bradley ControlLogix. On my main screen, I have a START dryer pushbutton and a STOP dryer pushbutton. The logic uses these as a standard start-stop configuration to enable the dryer. I got called in one night recently because the operators were trying to stop the dryer and as soon as they released the stop button on the panel (Set up as a momentary pushbutton), the dryer would start back up on its own. The START pushbutton (also configured as a momentary pushbutton) remained in the "touched " state. This was confirmed when I looked into the Contrologix program. This bit remained in a true condition regardless of whether the button was pushed or not. I stopped the dryer by toggling the bit in the program. After everything was stopped, I tested the start button several times and it worked as normal and has been working normal to date.
I contacted AD Tech support and was told to check the tag name for the pushbutton and make sure it matched the program. OK. Then they said delete the object and recreate it and inport the tag name from the A-B database. OK. I'm not convinced that this was the cause of the problem. Tech support said it probably was not the panel. They had never heard of this situation before. Anyone else experience this issue?