an old bale openers machine

we will modifie a old bale opener machine and we use S7-300.There is a rail and A and B side of the cotton bales available.If the request came from the silo head is moving on the rail.and flapping cottons until the entered value on the HMI screen.One each magnet is placed on the start and end of the cotton bales.There is one switch in moving on the rail head and changing the position of a magnet retains its position until the other magnets.My question is (continuous requests while) how this moving head goes forward and comes back ?I could not understand,any idea,thanks for advance...

I have not seen a bale opener machine. Have you made a list of inputs and outputs. Can you make a sequence of events chart for the machine? This will help us understand exactly what you want to happen.

Regards,
Garry
http://www.accautomation.ca

ttps://www.youtube.com/watch?v=d1uNZbIRRjc
It is showing machine.But we dont have sequence of events chart of machine.

Interesting video.
Based upon the following inputs:
Start, Stop, Magnet Sensor 1, magnet sensor 2
If you have the magnet sensor 1 and the start button is pressed then go forward. This would be a latched bit and memory retentive.
When the Magnet sensor 2 is activated it will stop reverse direction. This will continue until magnet sensor 1 is hit or stop is hit.

The next step would be to list all of the inputs and outputs of the machine.

Regards,
Garry
http://www.accautomation.ca