Input with Range Monitoring (v1.3)

Lib.Mervis.v1_3.SafeInput

The auxiliary block is used for monitoring the range of the input variable, filtering it, and potentially switching to a backup value.

  • Lib.Mervis
program test
    var
        inp: lib.mervis.v1_3.SafeInput;
    end_var

    inp();
end_program
Inputs Name Data TypeRetainMandatory Connection Meaning
AlarmPriority AlarmPriorityTypeNo No Class of generated alarm
Input real No Yes Input value
Minimum real No No Minimum allowed value
Maximum real No No Maximum allowed value
Hysteresis real No No Hysteresis around Minimum and Maximum
SafeInput real No No Backup value in case of failure
FilterTimeConstanttime No No Time constant of the filter for value filtering. If it has a zero value (t#0s), no filtering is performed
Override bool No No Input for forced switching to backup value
OutputsName Data Type Meaning
Alarm AlarmTriggerTrigger variable for alarm
Output real Output

The block is used to handle the value, for example from sensors, where in the case of its failure it is replaced by a safe value to prevent inappropriate action by the following blocks. If the Override input is true, it forces a switch to the safe value and simultaneously triggers an alarm state. A failure is considered when:

  • The input value is outside the Minimum - Maximum range
  • The value is NaN (not a number)
  • The value is +inf, -inf
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