How can I interlock a joint move on IRBP B250 positioner?

while test running a routine I had the table on the load side reposition.  I had one side all set then copied and pasted to new path and workobject, and changed my ActUnit/DeactUnit to the correct side.  I missed one, luckily it was during a test and no one was working in the load area.  

My first thought was to do a IF statement before each table reposition move to look at load side input and ActUnit callout, but that leaves the possibility for something to get missed again.  I'm new to programing, I'm not sure how to setup a back round Task or a trap routine any help would be much appreciated.