12_CH BCU control units are three different types. Number of fiber optic channels differs between these types.
BCU-02 2CH BCU-12 7CH BCU-22 12CH
BCU-02 can be replaced with BCU-12 or BCU-22. And similarly BCU-12 can be replaced with BCU-22. BCU-22 is recommended to be used as a stored spare part, because it is the most multiple use Using larger Control Unit instead of smaller one is "plug and play"(ACS880 only).