Unitronics IO-D18-RO8 I/O Expansion Modules 8 Inputs 8 Outputs The interface between a module and the OPLC is provided by an adapter. These modules may either be snapmounted on a DIN rail, or screw-mounted onto a mounting plate. Unitronics IO-D18-RO8 I/O Expansion Modules. byJuly 5, 2026