If the CPU access level allows online diagnostics (e.g., Read Access or HMI Access): Open TIA Portal and navigate to the . Double-click on Online & Diagnostics under the target PLC. Expand the Functions folder. Select Reset to Factory Settings .
Locks individual software blocks (FCs, FBs, DBs) within the project file. If you lose a Know-How password, those specific blocks cannot be edited or viewed, even if you have full access to the hardware CPU. Best Practices for Password Management in Industrial Plants
If the CPU is set to "No Access" and you cannot establish an online diagnostic connection, a physical Siemens SIMATIC Memory Card (SMC) is required.
Anyone can read, write, modify, or delete the PLC program. S7-1200 Password Unlock
The CPU is now at factory defaults and ready for a new program download. Method 2: Reset via TIA Portal (Online & Diagnostics)
To prevent the need for an in the future, follow these best practices:
For newer firmware, the only guaranteed software-free reset is: If the CPU access level allows online diagnostics (e
Siemens does not have a master override. Encrypted Logic: Passwords are not stored in plain text.
Open TIA Portal, find the card under Card Reader/USB memory in the project tree, right-click it, and select Format . Choose the Empty Card format profile. This deletes all previous configurations and sets the card to an initialization state.
Click on Reset to factory settings . You will be given options to keep or delete the IP address. Select your preference and click the Reset button. Select Reset to Factory Settings
A specific block or function block (FB/FC) is locked, rather than the entire PLC. 2. Authorized Methods for S7-1200 Password Recovery
Open the top flap of the S7-1200 and insert the empty SMC into the slot. Power Up the PLC: Turn the power supply back on.
Modern S7-1200 firmware versions (V4.0 and higher) use robust cryptographic algorithms to hash passwords before storing them. The plain-text password is never saved on the hardware or the memory card. Third-Party Software Risks
The "Password to Open" that prevents unauthorized users from uploading, downloading, or monitoring the PLC. The Hard Truth: Can You Crack the Password?