SNMP Driver Object Identifiers

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An Object Identifier or OID is used to identify a node in a hierarchy. An Object Identifier consists of a sequence of numbers, where the first number identifies the root node and subsequent numbers identify subnodes. For example the object identifier represents the sysDescr property of an SNMP Agent. The numbers in this sequence represent: iso(1), org(3), dod(6), internet(1), mgmt(2), mib-2(1), system(1), sysDescr(1).

The most common object identifier prefixes are (mib-2) and (enterprises).

Finding Object Identifiers

The Internet Engineering Task Force document RFC1213 defines the hierarchy below (mib-2). Examples of mib-2 object identifiers include:

Object Identifier
The description of the SNMP Agent
The elapsed time since the SNMP agent was started
The total number of received IP datagrams
The total number of discarded IP datagrams due an unknown protocol
The total number of TCP segments received
The total number of TCP segments sent

Any organization can define their own custom hierarchy to identify data not defined in the mib-2 standard. Each organization is allocated a unique private enterprise number (PEN) by the Internet Assigned Numbers Authority (IANA). Examples of some private enterprise numbers (PEN) include:

OrganizationPENObject Identifier
Siemens AG Automation & Drives41961.
Omron Corporation168381.

Organizations are free to define their own hierarchy below their private enterprise object identifier. Organizations define their own hierarchy using MIB files, and usually make these available on their product support website.

You can view MIB files in any text editor. As an alternative you can use a MIB browser, for example SnmpB.

Further Information

SNMP Client Driver

For an overview of the SNMP Client Driver.

Fernhill SCADA Drivers

For information about other drivers available in Fernhill SCADA.


For the meaning of terms used in Fernhill SCADA.