Each Gasmonitor Plus rack consists of a display module, a card frame that will accept up to sixteen input modules, an input/output module, a data logger and software. The operating voltage of the rack is 24Vdc. 100/230Vac power supplies and back-up batteries must be ordered separately. Dedicated 24 V alarm outputs power a maximum of two audible/visual alarms per rack. Additional alarm devices can be activated using relay modules.