Technical data

www.westermo.com Theoretical and general applications 141
MIB
Each agent in the network has a set of MIBs (Management Information Base), a MIB is
an object that can be called by a manager. Information can either be standard informa-
tion such as port status or port state, or company specific MIBs (private) for example
the temperature inside the device.
MIBs are structured tables made up of the different objects that can be called.
The structure can be compared to a tree with a root and underlying directories.
On the lowest level are directories for the standard MIB and for private MIBs.
OPC
An alternative to SNMP is OPC, which is an acronym for OLE for Process Control.
This is a series of standards specified for information exchange within industrial
automation. One of the purposes of these standards is to improve efficiency and
minimise the need of supplier specific drivers. Numerous different drivers usually
results in complex implementation as several applications need to interact and
exchange information.
The OPC specifications include functions for:
… OPC Data Access or (OPC DA) Access of data between applications, exchange of
information between systems in real time.
… OPC Historical Data Access (OPC HDA) used for historical process data and
analysing trends.
… OPC Alarm and Events (OPC A&E) Control of alarms and events.
… OPC Data eXchange (OPC DX) defines how the exchange of data should occur
between different OPC servers.
ROOT
CCITT (0)
ISO (1)
JOINT (2) ORG (3)
DOD (6)
Internet (1) DIR (1)
MGMT (2)
EXP (3)
PRIVATE (4)
SECURITY (5)
SNMPv2
(
6
)
MIB-2 (1)
ENTERPRISE (1)
B A C K