How to protect my unity pro plc from unauthorized access & connection
They are many ways to protect programs in Unity Pro using integrated protection functions or restricting access with the security editor.
Nevertheless, these protections cannot avoid stopping the PLC, modifying the program, or uploading a new application from another Unity Pro station which has no access right.
Unity Pro use a reservation mode when it is connected in programming mode with a PLC. This is to avoid other programming connections on the same PLC.
Others Unity Pro stations can connect to the PLC in monitoring mode with a limited access to the program and forbidding to take actions like stop the PLC, Modify the program or upload a new
application. Note: Monitoring mode does not forbid data modification and application download.
The tip is to let Unity Pro believe, that the PLC is already reserved and this is done by using a DFB . For that we will use a DFB which will reserve the PLC, allowing only monitoring connections,regardless of where the connection comes. Deactivation of the reservation mode will be done using a password. It is preferable to protect the DFB code, in a real application. In the exemple the DFB is not protected,
allowing modifications. Two DFBs have been created because addressing in Premium Quantum is different from M340 PLC.
These DFBs use two UMAS requests umas_TakePlcReservation 0x10 and umas_ReleasePlcReservation 0x11. Enclosed is a DFB's and the sample unity file.