How Can I Use Passwords To Protect PLC Programs From Being Downloaded Or Edited By Online Edit?

Whole Program Protection

The following program should be written in the first rung in the PLC:
Note Not supported by PLCs with no AR area e.g. C2OP etc )

Partial Program Protection From A Certain Contact To End

(Note, NOT for CQM1, CQM1H)
AR1002 can be used as the contact for the above ladder diagram. Then partial program which is later than LD AR1002 is protected.
When both LD AR1001 and LD AR1002 are used, LD AR1001 has more priority. Thus the whole program is protected.When LD AR1002 is used at two locations, the program is protected from the first LD AR1001.
An example of Partial Program Protection

Without releasing the password in the programming tool, you will get the partial program back and many 'NOP' instructions.

Download without using the password