Question re :roundrobin,

I wonder how to let each operator return after moves one item in a round robin fashion??
Thank you so much!

what I mean is the Operator go back to stand in a area close to the Machine and let next Operator fetch the next item and go back too , in a round-robin fashion..

You are using Round Robin in the Pass To of the Dispatcher, which is already the solution for using the Operator in round robin fashion. This is working. I personally would put in the OnReset Trigger of the Dispather the line setlabelnum(current,"fs_lastport",1); that the first Operator is always used first.
To send the Operator back to a specific point I would use e.g. in the OnUnload Trigger of the Operator the “Travel back to a Specific Location” or “Travel to an object”. For location you just need to figure out which location you like. For object you could put dummy objects (like Network Node or Visual Tool just to have an object with location) and center connect them with the Operator. Or you center connect the Operator with the Processor and calculate from his position a “parking position” (xloc + xsize + X).

I'm trying to do something similar, but I can't get the operator to return to the specified location. I'm using the operator for a process, so it's not really "unloading" anything. Is there a way to get the operator to return to a position while being used in conjunction with a process?

I was using the wrong trigger. "OnAvailable Resource" was the trigger I should be using. Sorry!