Didactum's IP-based hazard and alarm systems offer virtual sensors and elements.

These virtual sensors can consist of the following elements (as of March 2018):

Logic and rules from the logical schema

Timer functions

Trigger functions

Ping functions from predefined IP addresses (e.g., Google servers)

SNMPget functions

Editor's note:

To set up and manage virtual sensors in the IT monitoring system, the "virtual devices" option must be enabled in the user account.

Snmpget is used to monitor important information from external devices or elements by means of the SNMP protocol (Simple Network Management Protocol) integrated into the TCP/IP protocol.

The following queries can be performed via the snmpget command using the Didactum IT monitoring systems:

addsnmpget – add a virtual device via snmpget.

The following options are available:

• k – user session ID;
• id – element ID; if no ID is given, a new element is created.
• name – label of the element (maximum length 63 characters).
• period – polling interval in seconds (recommended 60, minimum 15).
• server – hostname or IP address of the monitored host (maximum length 255 characters).
• port – port number (default 161).
• version – SNMP version to use; choose v1 or v2c.
• community – SNMP community name, e.g. “public” (maximum length 30 characters).
• oid – object identifier (OID).
• vartype – variable type; required only when creating a new element. The corresponding output type for the virtual device:

1. analog – analog type (clas=analog, type=snmpget).
2. discrete – discrete type (clas=discrete, type=snmpget).

• expr – expression depending on vartype (maximum length 80 characters):

1. for an analog variable, formula f(x) to compute the real value (x is default);
2. for a discrete variable, the “normal” state of the element (mandatory).

• low_alarm – low alarm threshold.
• low_warning – low warning threshold.
• high_warning – high warning threshold.
• high_alarm – high alarm threshold.
• hysteresis – a sensor hysteresis can also be defined.

After a new virtual element is successfully created in the IT monitoring system, the response looks like this:

<error type="no error" id="505001" />

Note from the editorial team:

When creating a new element (no ID given) with vartype = analog, the following parameters must be defined:

low_alarm, low_warning, high_warning, high_alarm.

If vartype = discrete is defined, the parameters low_alarm, low_warning, high_warning, high_alarm are optional; however all other query parameters must be set. Empty fields are not allowed.

The command delsnmpget – removes the virtual snmpget sensor / virtual element. The following options are available:

• k – user session ID;
• id – element ID.

The command getelement – reads the element. The following options are available:

• k – user session ID;
• id – element ID.

Example:

<element id="505001" module="2011" num="1" clas="analog" type="snmpget" name="TestSNMPGET" state="high warning" value="3.02" status="working" period="60" server="192.168.1.190" port="161" community="read" oid=".1.3.6.1.4.1.39052.1.3.1.9.201001" low_alarm="0.0" low_warning="1.0" high_warning="2.0" high_alarm="3.0" expr="0.1*x" />