Push the toggle down to the MRES position and hold it firmly. The STOP LED will begin to blink slowly. Hold it for roughly 9 seconds until the LED turns solid yellow.

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S7-300 PLC 的密码保护体系主要分为三个层面。

S7-300 支持 4 种不同的保护状态，分别为：完全权限（无密码）、只读权限（可读不可写）、最低权限（仅可监控数据）和不允许上传。

If the default password doesn't work, follow the password reset procedure:

Before attempting a bypass, you must understand how the S7-300 handles security. Siemens utilizes three primary levels of password protection within its STEP 7 engineering software:

You lose all data, but the PLC is now accessible for a new download. Password Extraction Tools

Modifying or bypassing security measures on industrial control equipment must comply with strict corporate and legal guidelines: