The CS22 communications board is the slave board for the rack coupling via fiber-optic cable. The connection to the master board is inserted via two fiber-optic cable connections on the front panel.

Either a CS12, CS13 or CS14 board is used as master.

The address-, data- and control signals for accessing the master board memory are processed on the CS22.

Data transfer between the processor boards and the CS22 is realized via the C bus. Thus, it can only be used in subracks with L- and C bus.

The subrack with the CS22 can be considered to be the system slave. The basic sampling time and alarm interrupt from the master board are received, which can be used to synchronize the slave subrack.
Siemens Teleperm XP (T2000)