What To Do If You Forget The Cpu Password - Siemens SIMATIC S7-200 System Manual

What to Do If You Forget the CPU Password

If you forget the CPU password, you must clear the CPU memory and reload your
program. Clearing the CPU memory puts the CPU in STOP mode and resets the
CPU to the factory-set defaults, except for the CPU address, baud rate, and the
time-of-day clock.
To clear your program in the CPU, select the PLC > Clear... menu command to
display the Clear dialog box. Select all three blocks and confirm your action by
clicking the OK button. If you have a password configured, a
password-authorization dialog box is displayed. Entering the Clear password
(clearplc) allows you to continue the Clear All operation.
The Clear All operation does not remove the program from a memory cartridge.
Since the memory cartridge stores the password along with the program, you must
also reprogram the memory cartridge to remove the lost password.
Warning
!
Clearing the CPU memory causes the outputs to turn off (or in the case of an
analog output, to be frozen at a specific value).
If the S7-200 CPU is connected to equipment when you clear the CPU memory,
changes in the state of the outputs can be transmitted to the equipment. If you had
configured the "safe state" for the outputs to be different from the factory settings,
changes in the outputs could cause unpredictable operation of your equipment,
which could also cause death or serious injury to personnel, and/or damage to
equipment.
Always follow appropriate safety precautions and ensure that your process is in a
safe state before clearing the CPU memory.
S7-200 Programmable Controller System Manual
A5E00066097-02
Basic Concepts for Programming an S7-200 CPU
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