If the "Read" protection is enabled, you cannot perform an "Upload to PG" action. You will receive a password prompt.
Never attempt a hex edit or third-party unlock without a raw image backup of the MMC.
List the user who set the password and the date in the project comments. unlock s7300 plc password work
Store all industrial passwords in secure, role-based enterprise vaults rather than relying on individual engineers' local text files.
However, Siemens does offer a function (MRES), which clears the password and the program. As mentioned above, this is only useful if you have a backup of the code. If the "Read" protection is enabled, you cannot
Pull the Micro Memory Card (MMC) out and reinsert it, or perform a "Memory Reset" (MRES) sequence using the toggle switch.
Unlocking or resetting a password on a Siemens SIMATIC S7-300 PLC depends on whether you have the original project files and what level of access you need. 1. Standard Reset (Factory Default) List the user who set the password and
"You can NOT break the password, and that's why it is there in the first place. So no unauthorised person will be tempted to play with the program/device/production/plant etc." — Siemens Support Forum
In an industrial context, the "proper feature" related to password handling on the Siemens S7-300 platform is and the Master Password mechanism.
Save the changes, open STEP 7, and open the block. The code will now be visible. Method 3: The Complete Factory Reset (Data Erasure)