Trending is a possible option, however, some PLC's do not have it, The OP is using an HMI but assuming one input (presumably a conveyor in this case) then the others shut off as well according to the OP, this means it could happen quite quickly, The HMI would probably not pick it up due to coms latency, or the amount of memory required to store a very fast trand of say 10 inputs for enough time for a check on what was switched off would probably exeed the memory capacity, so in reality, probably not a practical option. I also believe that there is possibly an idea to have an indicator on each conveyor or what ever showing which one was stopped first.