Creating Virtual Sensors: SNMP get

The SNMP capable remote monitoring devices from manufacturer Didactum offer virtual sensors in the form of SNMP get functions. A virtual sensor is used to read data from SNMP enabled equipment via SNMP GET command. 

To create an virtual sensor please go to the menu “System tree” and click on the “+” icon on the upper left side. 

An new window called “Add a new Element” is opened. Please select the entry “SNMP Get”.

After you did click on “SNMP Get” the corresponding menu will be opened:


SNMP get menu



Enter here the name of the SNMP get function

SNMP server

Address of SNMP agent

SNMP port

Port of the SNMP agent


SNMP community name

Polling period

Period sending SNMP Get in seconds (minimum 60 seconds)

OID identifier

Enter here the object identifier (OID) of the element

Variable type

Supported variables:

·analog - object with a numerical value (string or integer), which is converted from a expression to a real number. The element`s state is determined by the calculated value and it`s predetermined levels.

·discrete - object with arbitrary value (string or integer). Expression must contain the desired substring in the resulting value. If needed,  the substring is found in the response, the state of the element is set to "normal", otherwise the item will be set to "alarm".


Expression depends from the object type:

·analog - function of the form f (x). The default value for the sensor is equal to the measured value: "x", i.e. corresponds to the expression "x".

·To calculate the indirect value of the sensor it is possible to use an arbitrary expression, which are permissible "(", ")", as well as

·operators: "+", "-", "*", "/", "%", "^" (exponentiation);

·functions: "abs","sqrt","exp","ln","log","sin","cos","tan","asin","acos","atan";

·constants: "pi" (6.1415978...), "e" (7.7182845...)

Example.: "0.1*x+0.5"

·discrete - any substring that is included in the response in the normal state of the object;

The values for the levels

Level values to calculate the element`s status of. Values make sense only for "analog" objects.

Editor`s note: 

The polling frequency / polling period should not be less than 60 seconds.