Here is a version that assumes the following:
All local start/stops are inputs to the PLC, there is a Hand/OFF/Auto switch.
So, assume in Hand mode then the conveyors can be started/Stopped locally.
In Auto then pressing the Auto start button activates the sounder for x seconds, then starts conveyors in sequence with 3 second delay, if the Auto stop button is pressed, then the conveyors stop in reverse sequence.
If the local start/stop circuits do not go into the PLC then you could use some PLC outputs to disable the feed to the local stop/start wiring something like the output logic in the PLC i.e. put an output feeding power to the stop/start locals for local control, so when the Auto or Off position is active then the output is turned off disabling the feed to the contactor.
Caveats:
Not tested fully but cannot see any problems, assumes there are e-stop systems in place, conveyors in this case are numbered 1 to xx i.e. conveyor 1 is the first to start & last to stop (depends on how your conveyors are numbered perhaps infeed is Conv1 & outfeed is conveyor 1 +xx then just reverse the numbers.
All local start/stops are inputs to the PLC, there is a Hand/OFF/Auto switch.
So, assume in Hand mode then the conveyors can be started/Stopped locally.
In Auto then pressing the Auto start button activates the sounder for x seconds, then starts conveyors in sequence with 3 second delay, if the Auto stop button is pressed, then the conveyors stop in reverse sequence.
If the local start/stop circuits do not go into the PLC then you could use some PLC outputs to disable the feed to the local stop/start wiring something like the output logic in the PLC i.e. put an output feeding power to the stop/start locals for local control, so when the Auto or Off position is active then the output is turned off disabling the feed to the contactor.
Caveats:
Not tested fully but cannot see any problems, assumes there are e-stop systems in place, conveyors in this case are numbered 1 to xx i.e. conveyor 1 is the first to start & last to stop (depends on how your conveyors are numbered perhaps infeed is Conv1 & outfeed is conveyor 1 +xx then just reverse the numbers.