Analog sensors

Owned by Vladimir Tayzhev
Last updated: Oct 27, 2023
2 min read

Vutlan analog sensors have analog inputs and analog or discrete outputs.

If the analog sensor is not connected or undefined, such sensor will be in a state of 'not connected'.

The analog sensor parameters of the VUTLAN devices can be located depending on their physical location in the sub-branches:

  • ctlInternalSensors - main system sensors;

    • ctlInternalSensorsAnalogsTable;

  • ctlCANSensors - CAN bus sensors;

    • ctlCANSensorsAnalogsTable;

  • ctlRsSensors - serial port sensors;

    • ctlRsSensorsAnalogsTable;

Example. Viewing analog sensors:

$ snmptable -Ci -Cb -v2c -cread 192.168.0.193 VUTLAN-SYSTEM-MIB::ctlInternalSensorsAnalogsTable



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SNMP table: VUTLAN-SYSTEM-MIB::ctlInternalSensorsAnalogsTable
 
     Id Module Num          Type          Name          State  Value     Min    Max LowAlarm LowWarning HighWarning HighAlarm   At0  At75 Expression Specific
 201001      2001    -1  "temperature"  "Temperature"      "high alarm"  "34.2"  "-50.0" "110.0"       "5.0"          "10.0"            "15.0"        "20.0"   "1.0"  "0.0"        "x"       ""
 203001      2001    -2          "voltage"          "Voltage"            "warning"  "11.3"      "0.0"   "24.0"       "5.0"          "10.0"            "15.0"        "20.0"   "1.0"  "0.0"        "x"       ""
 204001      2002      2        "fvoltage"        "Analog-2"        "low alarm"    "0.0"      "0.0"   "10.0"       "5.0"          "10.0"            "15.0"        "20.0"   "1.0"  "0.0"        "x"       ""
 201002      2002      3  "temperature"        "Analog-3"      "high alarm"  "27.5"  "-50.0" "110.0"       "5.0"          "10.0"            "15.0"        "20.0"   "1.0"  "0.0"        "x"       ""

The location of such sensors in the system is determined by the module identifier in which this element is physically located and with the port number in the module - Num.

 

Sensor with analog output can be in one of the following states defined with thresholds ctlAnalogLowAlarm, ctlAnalogLowWarning, ctlAnalogHighWarning, ctlAnalogHighAlarm:

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

  • 'low alarm' - below normal, the measured value is below the threshold ctlAnalogLowAlarm;

  • 'low warning' - below normal, the measured value is above the threshold ctlAnalogLowAlarm, but below the threshold ctlAnalogLowWarning;

  • 'high warning' - above normal, the measured value is above the threshold ctlAnalogHighWarning, but below the threshold ctlAnalogHighAlarm;

  • 'high alarm' - measured value is above the threshold ctlAnalogHighAlarm;

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:

U=ctlAnalogAT0*U0+ctlAnalogAT75

 

Field ctlAnalogExpression (default "x") has meaning only for the current sensor (4-20mA), and sets the expression to convert the measured value:

Value=ctlAnalogExpression(x)

 

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

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

Support the following functions:

  • "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 sensor with analog output with ElementID=22:

$ snmpset -v2c -cwrite 192.168.0.193 VUTLAN-SYSTEM-MIB::ctlAnalogLowAlarm.2 s "5" \ VUTLAN-SYSTEM-MIB::ctlAnalogLowWarning.2 s "35" VUTLAN-SYSTEM-MIB::ctlAnalogHighAlarm.2 s "45" VUTLAN-SYSTEM-MIB::ctlAnalogLowAlarm.2 = STRING: "5" VUTLAN-SYSTEM-MIB::ctlAnalogLowWarning.2 = STRING: "35" VUTLAN-SYSTEM-MIB::ctlAnalogHighAlarm.2 = STRING: "45"