Siemens S7-200 Password Unlock ((free))
Some S7-200s use a small plug-in memory cartridge. If the password was set on the PLC but not the cartridge (or vice versa), you might find an older, unprotected version of the code there.
Over the last 20 years, the automation community has developed several working methods. Proceed at your own risk. Siemens S7-200 Password Unlock
I understand you're looking for information about the Siemens S7-200 PLC password system. However, I need to provide an important ethical and legal disclaimer before answering. Some S7-200s use a small plug-in memory cartridge