Analog Sensors from Didactum

The Analog Didactum Sensors have analog inputs and analog or discrete outputs. If an analog sensor is not connected or undefined, it will be in a state 'not connected'.

The analog sensor port number to which the sensor is connected, is determined by the field ctlAnalogHardwarePort
You can view analog sensors with
snmptable -Ci -Cb -v2c -cread DIDACTUM-SYSTEM-MIB::ctlAnalogsTable


Reading of Didactum`s analog sensors

The readings of Analog Sensors are in the field ctlAnalogValue.

Sensors with analog output can be in one of the following states defined with thresholds ctlAnalogLow, ctlAnalogWarning, ctlAnalogAlarm:

  • 'normal' - the measured value is above the threshold ctlAnalogLow, but below the threshold ctlAnalogWarning, ctlAnalogAlarm;
  • 'low' - below normal, the measured value is below the threshold ctlAnalogLow, ctlAnalogWarning, ctlAnalogAlarm;
  • 'warning' - above normal, the measured value is above the threshold ctlAnalogLow, ctlAnalogWarning, but below the threshold ctlAnalogAlarm;
  • 'alarm' - measured value is above the thresholds ctlAnalogLow, ctlAnalogWarning, ctlAnalogAlarm;

The fields ctlAnalogAT0 (default "1.0") and ctlAnalogAT75 (default "0.0") are only for the voltage sensors and set the coefficients to convert the measured value using the following formula:


The field ctlAnalogExpression (default "x") is used only for Didactum`s 4-20mAmp sensor (4-20mA), and sets the expression to convert the measured value:


The default readings correspond to the measured values with no additional changes.

It supports the following operations: "+", "-", "/", "*", "%"(modulo), "^"(involution)
Following functions are supported

  • "abs" - absolute value;
  • "sqrt" - square root;
  • "exp" - exponential;
  • "ln" - the natural logarithm;
  • "log" - logarithm;
  • "sin" - sine;
  • "cos" - cosine;
  • "tan" - tangent;
  • "asin" - arc sine;
  • "acos" - arc cosine;
  • "atan" - arc tangent;

Example: Setting thresholds for a Didactum sensor with analog output with ElementID=22:

  1. $ snmpset -v2c -cwrite DIDACTUM-SYSTEM-MIB::ctlAnalogLow.2 s "5" \
  2. Didactum-SYSTEM-MIB::ctlAnalogWarning.2 s "35“ DIDACTUM-SYSTEM-MIB::ctlAnalogAlarm.2 s "45"
  4. DIDACTUM-SYSTEM-MIB::ctlAnalogLow.2 = STRING: "5"
  5. DIDACTUM-SYSTEM-MIB::ctlAnalogWarning.2 = STRING: "35"
  6. DIDACTUM-SYSTEM-MIB::ctlAnalogAlarm.2 = STRING: "45"

Didactum sensors with discrete output

Didactum sensors with a discrete output have following two states: „normal" or „alarm"

If needed, the inversion is performed by setting the state '1' in a field ctlAnalogReversed (default '0').

Thresholds ctlAnalogLow, ctlAnalogWarning, ctlAnalogAlarm do not affect the status of such sensor.
Sensor readings are in the field ctlAnalogValue and can take values '1.', or '0.‘
Example: Set up of an inversion of the Didactum sensor with a discrete output ElementID=20:

$ snmpset -v2c -cwrite DIDACTUM-SYSTEM-MIB::ctlAnalogReversed.0 i 1