The base units PNOZmulti 2 are modular and expandable and meet PL e (EN ISO 13849-1) and SIL CL 3 (IEC 62061). The base units PNOZ m B0 and PNOZ m B1 can be expanded on the left-hand side with max. 4 expansion modules, max. 1 communication module and max. 1 fieldbus module. PNOZ m B0 can be expanded on the right-hand side with 6 expansion modules, while PNOZ m B1 can have a max. of 13. PNOZ m B1 has no inputs or outputs, except for 4 test pulse outputs.