PLC Siemens CPUs

Siemens S7 manual See page 20.

Dear Friend the problem is that I need to Upload the program from the CPU to my PG but I can not because of the CPU is protected by password

The next thing I would do is try to track down the last person to have full access to the PLC. I'm guessing you already tried this but I had to say it anyways. The next possibility is to clear the CPU but only if the program was saved to the EPROM or non-volitile memory. Once the CPU is cleared, powered down and then restarted the password protection should be cleared according to the "FAQ" at the Siemens website and the program should reload from the EPROM.

Siemens FAQ for "reset access"

Often Programmers that feel the need to install passwords on customer systems will use the companies name or initials. When I first started working for my current company everything was password protected with 'USF', so try a few combinations of your companies name or any common passwords that might be in use elsewhere.

As general rule, unless there is a specific requirement to password a PLC.... Don't. If the use of passwords is required then make sure a copy of the password is kept in a firesafe.

saearch this website http://www.plctalk.net/qanda/ and you may find some clues on how to get in through a backdoor. Or contact your local Siemens office.