The Reliability property on an input returns Under Range even though the Electric Value is within the Reliability level range.

Issue

On an input configured with an Engineering Value range of 0 to 5 Degrees Celsius, an electric scale range 470 ohms to 10470 ohms and a reliability range from 470 to 1047 ohms, any input value produces an Under Range in the Reliability Property value.

Product Line

SmartStruxure Solution

Environment

  • SBO
  • AS
  • Inputs
  • Reliability
  • BACnet

Cause

The Reliability property references the inputs Engineering Values, not the Electrical Values.

Resolution

Because the Reliability parameters that are set on SmartStruxure inputs reference the Engineering values, in this example even the maximum value of 5 degrees Celsius would have placed the input value far below the Lower Reliability Level parameter of 470 (ohms). 

In this case the solution is to use an Lower Reliability Level of 0 and an Upper Reliability Level of 5.