I have a new application that involves palletizing 5x5 plastic forms. The stack will be 9x9. We will be utilizing 2 UR 10's, 2 FT 300's and 2 140 grippers. The parts weight in a 12.2 KG's. This a two part question. We had a internal meeting on this project the other day and ruled out mirroring the robots due to the Joint positions not all being the same direction. Our Robot specialists feels we should use a PLC and HDMI to coordinate the movements between the robots. I don't like adding more components and difficulty for the customer. There are only 2 sensors involved with this app. Part present and Pallet present. Does anyone feel it is necessary for a PLC or can the robot handle this? What would be the best way to program this?

What coordination is required?  Are they lifting the same part at the same time or are they both packing the same pallet from two different lines?

we have 3 robots running presses with linear slides moving parts between the robots and in from the humans and out to the humans and no PLC. The robots use built in modbus registers to be able to share information with the other robots such as I’m in the way, don’t move the linear slide yet. We also use modbus to watch inputs and outputs that are attached to the other robots so that each of the robots can see the environment around itself regardless of where the inputs are attached. 

   Both robots are working together to lift the same part. One on each end. These parts are 144 inches long.

@tjcooper you could still use the robots to coordinate the motion, you would make one robot the master and one the slave, the master would tell the slave to begin motion and would start motion at the same time, the slave would then report when motion was complete and the master would wait to receive that command to move to the next step.  Ideally they are arriving at each point at the exact same time but if they aren't the master can't get ahead of the slave and the slave is always waiting for the master to move to the next position.  You can do this by simply writing to modus registers which the robots can read.

You would have the master write to a register with the slave monitoring the register to start a move, could have the master basically indexing through a sequence of steps with a wait command on the slave for the register to equal a certain value.  Then on the slave you would use a register to indicate start and stop of motion,  basically taking a register and changing the value as soon as the wait command is executed and then setting it back right before the wait command. 

This approach would allow you to coordinate motion with the two robots without the need for a separate PLC.  You can even have the master robot start the program for the other robot by using the dashboard server, then have the slave and master coordinate when the programs have started and reached a certain point in execution allowing each of them to have separate homing routines if needed.