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Analog Input Modules

An analog input (AI) module includes three independent input channels. Each input channel receives variable voltage signals from each point, converts them to digital values, and transmits the values to the three main processor modules on demand. In TMR mode, one value is then selected using a midvalue
selection algorithm to ensure correct data for every scan. Sensing of each input point is performed in a manner that prevents a single failure on one channel from affecting another channel. Each analog input module sustains complete, ongoing diagnostics for each channel.

Failure of any diagnostic on any channel activates the Fault indicator for the module, which in turn activates the chassis alarm signal. The module’s Fault indicator merely reports a channel fault, not a module failure—the module can operate properly with as many as two faulty channels.

Analog input modules support hotspare capability which allows online replacement of a faulty module. The analog input module requires a separate external termination panel (ETP) with a cable interface to the Tricon backplane. Each module is mechanically keyed for proper installation in a Tricon chassis.