The practical reality for a maintenance engineer is that if a PLC is Read/Write protected and there is no backup, the password is effectively permanent. The only safe "work" to be done is either negotiating with the IP owner for access or preparing to rewrite the automation logic from scratch. Zita Dans La Peau D39une Naturiste Doc Link
The Siemens SIMATIC S7-300 is a staple in the industrial automation industry. Due to its longevity, many of these controllers have been in operation for decades. A common scenario faced by maintenance engineers and integrators is encountering a "locked" PLC—a situation where the source code is protected by a password, and the original documentation or programmer is unavailable. 9 Empires Cheat Engine: Dynasty Warriors