The robustness of the system can be improved by implementing simple checks in software. The primary reason for this is to help with the loss of VCC or loss of GND fault condition.

Fault detection is typically done by measuring when the OUTx pins enter a High-Z state. This is done by adding pullup and pulldown resistors on the controller board. The ADC then measures if the OUTx signals ever exceed V_{OUT_FLT_HIGH} or are below V_{OUT_FLT_LOW}.

If a pullup resistor is used, a loss-of-VCC condition on the sensor board causes there to be a small leakage current (I_{OUT_NOVCC}) path into the OUTx pin. If a pulldown resistor is used, a loss of GND condition on the sensor board will have a leakage current path (I_{OUT_NOGND}) into OUTx pin. The leakage current value is controlled such that the OUTx pin voltages stay above V_{OUT_FLT_HIGH} and below V_{OUT_FLT_LOW}. However if certain application conditions cause the OUTx pin voltage outside the fault thresholds, following options is recommended to ensure that the MCU recognizes that a fault has occurred:

• Use a combination of pullup and pulldown resistors. This way, a loss of ground or loss of VCC will always be detected by two of the four OUTx pins. For example, if a pulldown resistor is present, then a loss of VCC can be signaled with a voltage below V_{OUT_FLT_LOW}. If a pullup resistor is used, then a loss of GND can be signaled with a voltage about V_{OUT_FLT_HIGH}.
• Track the common-mode voltage of the OUT0x and OUT1x pairs. Normally the common mode will be half of VCC. A loss of VCC or GND is easily caught by using this method. This method does not work when using single-ended mode.