adccommunitymod (AutomationDirect) asked a question.
Created Date: April 13,2015
Created By: dvcochran1
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Hello, I have an application where an operator loads a part onto a fixture and a pick & place vertically picks up the part and moves it away from the operator with vacuum cups. Currently there is a light curtain that is hard wired to kill most of the pneumatic solenoids, requiring the light curtain to be reset, stopping the process in mid-cycle if the curtain is broken at the "wrong " time. To prevent stoppage, the curtain can only be broken when the pick & place is all the way forward (farthest from the operator) and has lowered the part on the next station. I have been out of the control loop for a while and am more familiar with light curtain control on press applications where hard wiring is the norm. Since this in NOT a press app. and there are no safety issues, are there any regulations that would prevent me from using the safety relay signal as a PLC input and change the logic so that the curtain can be broken as soon as the pick & place has picked up the part and is moving AWAY from the operator? The P &P is servo so getting a signal should be no problem. I just want to be sure I am doing this safely. Thanks for the advise. David Cochran
Created Date: April 13,2015
Created by: dvcochran1
Hello,
I have an application where an operator loads a part onto a fixture and a pick & place vertically picks up the part and moves it away from the operator with vacuum cups. Currently there is a light curtain that is hard wired to kill most of the pneumatic solenoids, requiring the light curtain to be reset, stopping the process in mid-cycle if the curtain is broken at the "wrong " time. To prevent stoppage, the curtain can only be broken when the pick & place is all the way forward (farthest from the operator) and has lowered the part on the next station.
I have been out of the control loop for a while and am more familiar with light curtain control on press applications where hard wiring is the norm. Since this in NOT a press app. and there are no safety issues, are there any regulations that would prevent me from using the safety relay signal as a PLC input and change the logic so that the curtain can be broken as soon as the pick & place has picked up the part and is moving AWAY from the operator? The P&P is servo so getting a signal should be no problem. I just want to be sure I am doing this safely. Thanks for the advise.
David Cochran
Created Date: April 13,2015
Created by: Adisharr
Have you done a risk assessment on the machine? That's what is really comes down to. If there is any real chance of injury then using PLC logic to evaluate any safety logic is generally not allowed.
Is there a particular reason why they can't stop the process during any part of the cycle? I know the vacuum portion is usually an issue but there are ways to handle that.