the 1794-ib32 is a 24v dc sink input module. the 1794-ob32p is a 24v dc protected source output module. both use the special 1794-tb32 terminal base. the flex i/o 32-point module reduces the per point cost of a 24v dc digital i/o installation by providing twice as many i/o channels as 16-point flex i/o in the same amount of space, and at a fraction of the cost. using these modules, a flex i/o system can now support up to 256 digital i/o channels on a single network adapter, doubling its previous capability.