In an isolation system, different analog to digital converters (“ADCs”) are provided on a first side of an isolation barrier. Outputs from the ADCs may be merged into a common data stream and communicated across the isolation barrier by a single isolation device. The ADCs may sample independent signals or may sample a common signal. When the ADCs sample a common signal, the system may monitor the input signal for fault conditions. During no fault operation, results of an analog-to-digital conversion may be communicated across an isolation barrier by an isolation device. During a fault condition, data representing the fault condition may replace the ADC data in communication across the isolation barrier. Fault conditions may be signaled by unique data patterns that can be distinguished from ADC data.