GF80.35-W-3005A | Radio frequency remote control rolling code, function | 27.3.96 |
BODY 940.899, 942.899 with CODE (FZ1) Central locking with radio frequency remote control (ZVA)
BODY 940.899, 942.899 with CODE (FZ3) Convenience locking system with remote control
In addition to the fixed code the remote control also uses an additional rolling code in order to secure the data transfer between the remote controls and FFB control module against manipulation.
The rolling code changes automatically in the remote control as well as the FFB control module each time a command is transmitted. The remote controls and FFB control module are set to a common starting code at the plant.
Since the rolling code changes each time the remote control is actuated, it is possible that the next command from the remote control will no longer be recognized when a command is not received by the FFB control module. In order to avoid this the control module always calculates the codes for the next 200 commands and stores them in a memory.
The control module therefore always compares the rolling code received with the 200 values calculated previously ensuring
that the control module looses its access authorization only after 200 erroneous operations.
The rolling code for an old control module, which has reached the limit of 200 erroneous operations and therefore is no longer recognized by the FFB control module, can be learned in again by the customer or driver.