How to prevent PLC program download - Database & Sql Blog Articles

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Plc is Siemens S7-400, how to prevent others from downloading the program to the PLC, the method of the key switch hitting the RUN mode need not be mentioned. Is there any other way? The other one, how to lock the FC function block.
A: First: How to lock the FC function block?
1. Open the program editing window LAD/FBD/STL;
2. Convert the block generation to be cryptographically protected to a source code file (generated by selecting menu File->Generatesource);
3. Close your program block in the LAD/FBD/STL window and open the source file generated in the previous step in the source folder of the SIMATICManager project management window;
4. In the declaration section of the block, enter "KNOW_HOW_PROTECT" in the line below the TITLE line;
5. Save and compile the source file (select menu FileSave, FileCompile);
6. Now complete the encryption protection of your block;

Second: the steps to encrypt the CPU:
1, open the STEP7 program, and then open the hardware manager;
2, open the CPU properties of the PLC;
(Open method: double-click the CPU or right click and select ObjectProperties)
3. Select the Protection item in the properties dialog that opens;
4. Select 2 or 3 and enter the password in password and Enteragain.
5. Click OK, then compile the hardware and download it to the PLC.

Regarding the selection of Protection, the default is 1 when it is opened, that is, no protection (or keyswitchsetting); you choose 2 (write protection, this protection has a password can not be written to the program online, can only be read), or 3 (read and write include This protection can no longer read and write programs online without a password.
What you want is write protection, so you should choose 2.