I need a PLC programmer , S7-300

I need a program to run two baracoder simultaneously. So each product on the conveyor will have one stamp. So if the line has infeed both will work, first product will be stamped form coder 2 , 2nd product form coder1 ..etc. each baracode machine has one sensor. There is a sensor for the infeed. If one machine has fault the other will stamp each product automatically . I need in in ladder diagram with clear notes. Also I need design in wincc for the hmi