S5 with scada by pg port

[gendy]

hi i have old machine works with siemens s5 cpu 95u connected with computer running operation and monitoring software , connection on PG port, i haven't the original copy of application program i make upload from the plc (no symbole file ) i can only know the input and output from electrical drawing how can i know the data between pc and plc (the machine make a problem that when bar code check enables from pc all products rejected when we disable it from pc machine work good)