DO 3401 | Invensys Digital Output Module

The Digital Output (DO) Module contains the circuitry for three identical, isolatedchannels. Each channel includes a proprietary ASIC which receives its output tablefrom the I⁄O communication processor on its corresponding main processor. DOModules use special quad output circuitry to vote on the individual output signalsjust before they are applied to the load. This voter circuitry is based on parallelseries paths which pass power if the drivers for channels A and B, or channels Band C, or channels A and C command them to close; in other words, two out ofthree drivers are voted on. The quad output circuitry provides multiple redundancyfor all critical signal paths, guaranteeing safety and maximum availability.