The CS12 communications board is the master board for the rack coupling via fiber-optic cable. A CS22 slave board can be directly inserted at the front panel through two fiber-optic cable connections.

Data transfer between the processor boards and the CS12 memory is realized through the C bus. Thus, it can only be used in subracks with L- and C buses.

The CS12 has a memory, which can be accessed by all partners. The maximum memory size is 128 kbyte. There is arbitration between the individual nodes so that only one coupling partner can access the memory at any one time.

The ICS1 expansion board is inserted at connector X3. Up to four CS22 slave boards are connected to this board. The CS12 interface is disabled if an expansion board is inserted.

The subrack with the CS12 can be considered as master in the system. The base sampling time and alarm interrupt are transferred to the connected slave boards via the CS12. Thus, the slave subrack can be synchronized.
Siemens Teleperm XP (T2000)