The DI831 is a 16 channel 48 V d.c. digital input module for the S800 I/O. The input voltage range is 36 to 60 V d.c. and the input current is 4 mA at 48 V d.c.). Each input channel consists of current limiting components, EMC protection components, input state indication LED and optical isolation barrier. The module cyclically performs self-diagnostics. Module diagnostics include:

• Process power supply supervision (results in a module failure, if detected)
• Event queue full
• Time synchronization missing.

The input signals can be digitally filtered. The filter time can be set in the range 0 to 100 ms. This means that pulses shorter than the filter time are filtered out and pulses longer than specified filter time get through the filter.