Programming PLC

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Joined Feb 19, 2004

Is there any body who coul give me a hand how to make a ladder diagram with a small project that I'm working for ? Beacause I'm not familiar with PLC and its programing system. It's more on machine related problem that needs a long term corrective action to prevent a massive burn out of pcb substrate inside of reflow oven. At the output rail of reflow oven most of the time pcb got stock resulting to massive burn out of pcb, so I have designed a circuit that will will help us a lot to prevent the occurence of the said problem . Firstly I place a proximity sensor that will sense the presence of pcb at the end of the rail with a timer of 18 to 20 seconds, after that if the pcb were still there it will activate the coil of relay and one of the normally open contact will close and will acitivate the conveyor into inspection mode prior the input of reflow oven preventing any substrate to go inside of reflow oven.

I highly appreciate any help that you could give me .