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Control & PLC Stratagy for Robotic Cell
2

thread277-161589

Control & PLC Stratagy for Robotic Cell

Control & PLC Stratagy for Robotic Cell

(OP)
Simple question I Hope
I am setting up a Robotics cell to stack 45 pound bags, on a pallet

There are 5 Conveyors involved all with Photo eye inputs, stops, etc.

The question: Would it be better to use a seperate PLC such as a AB Micrologic or SLC to control the process I/O and safety I/O and simply give the Robot Controller a digital input to begin the stacking program.

The Robot Controller is an ABB S4 with its own I/O rack.

My only objection having the Robot act as a PLC is that the Maintenace Staff understands ladder Logic programming and Trouble shooting and not the Robot language.

Opinions appreciated

RE: Control & PLC Stratagy for Robotic Cell

All of my gray hairs agree with you.  Most 'bots these days can have some form of soft-PLC imbedded in it.  This would make the wiring / cost / labor less, in theory.  My experience is that it causes support problems on the factory floor.  Many times no one is trained on the 'bot stuff.  If they do, then they use that specific skill to seek another job and are gone.

Everybody and his brother still knows PLCs, even after all the years of hype about "PC Control".  The robot is rarely the problem, but it gets blamed for everything since it isn't moving.  In my opinion it's a better course of action to spend the money & effort to have a PLC control things because it can be supported by the 3rd Shift Maintenance Guy.   Then you are less likely to get those phone calls at 3:00AM about "your robot don't work".

IMHO, use the PLC to do what it's best at:  sequencing and control.  Use the robot to do what it is best at:  moving.  Make the PLC give the robot a "go do this now" signal and receive from the robot a "OK, I'm done" signal in return.

TygerDawg

RE: Control & PLC Stratagy for Robotic Cell

I have to agree with tygerdawg.  We had 3 robotic cells built for us 3 years ago (palletized load/unload of a CNC).  The machine builder tried to go only with the robot (Denso) as the cotroller but ran out of I/O, added a SLC and what a mess.  Robot is the master and plc the slave.  Maintenance has no clue as to what is going on.  I have tried to work with them, but to not much success.  Sometimes I feel like I do not know what is going on with it either.

Use a plc.  Make it the master and the robot the slave.  Binary program select to the robot and wait for a done signal to be returned.
Life will be much better for you and everone else in the end.  Good Luck.

RE: Control & PLC Stratagy for Robotic Cell

The purpose of the robot while being included into a production line is not that Master as Tygerdawg and Steve mentioned..

Although it has the option of additional IO points and logic coding the purpose for which it was built is not to control conveyer systems...

Few of the maintenance staff will ever get to the point where they could troubleshoot this..The robot is aslsothe last place where you want a faultfinding recking crue tostart testing voltages... Robot cabinet should be programmed and locked till the programmer/installation expert gets phoned in for his key..

RP

--Off all the things i've lost , i miss my mind the most--

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