OmniTek Ultra XR, Руководство пользователя

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Ultra XR User Guide C–11 XR-56-201 5
Applic
ations
SNMP Remote Control
Overview
The Omnitek Ultra is highly suited to being used in routine monitoring applications through its support
for remote control using the SNMP protocol. SNMP stands for Simple Network Management Protocol
and it is commonly used in production line testing both to run the required sequence of tests and to
monitor the instrument under test for conditions that warrant attention.
Both parameter values and system controls are available for read and write access across a network
potentially covering many Ultra systems, allowing the development of dedicated systems to carry out
standardised test procedures and so free engineers to concentrate on fixing issues where and when
they arise.
This aspect of the Ultra is both versatile and easy to program. An example application, written using
Microsoft Visual Studio together with the SnmpSharpNet SNMP library, is available to registered users
from the Downloads page of the Omnitek website (www.omnitek.tv/download).
Background
The SNMP Protocol is based around the association of Object Identifiers (OIDs) with system parameters
and controls. The settings of these parameters and controls are read and written (where allowed)
through Get and Set commands made using these OIDs by whichever application is being used as the
‘SNMP Manager’.
In order to make appropriate use the OIDs, the SNMP Manager requires details both of the range of
OIDs used and how these are mapped onto the facilities of the equipment that is being monitored. It
also needs to know what type of data each item comprises. This data is provided in the form of a MIB
(Management Information Base) file.
Each MIB file is unique to the manufacturer of the system it is being used with but that manufacturer
can choose to use the same MIB file across a number of similar systems and across different versions
of a system. The MIB file provided with any Ultra system will always be backwards compatible with
earlier versions of this MIB file but you are advised to always update to the latest version in order to
take advantage of the latest features.
A number of commercial SNMP Managers are available, many providing a ‘MIB Browser’ that can be
used to ‘walk through’ the MIB file and display both the OID and the current value of each parameter/
control. MIB Browsers typically also offer facilities for changing the configuration by writing to the
appropriate parameter/control where allowed.
Also available are libraries offering specific support for programming SNMP applications for use
alongside standard programming languages such as C and C++.
A primary use of SNMP is in the application of the test and monitoring procedures across a number of
similar systems, all networked together. Each system is individually accessed using its address on the
network but, for easier recognition, SNMP allows you to set a name and location for each machine.
The name and location that have been set are among the details that can be returned from machines
accessed using SNMP.