On a ClearSCADA system, you configure the ClearSCADA database so that entries in the database correspond to the devices on your system. In the case of the SNMP driver, you configure an SNMP point for each data value that ClearSCADA is to retrieve from an SNMP agent.
To configure the points and to retrieve data using the SNMP protocol, the SNMP Driver has to be installed and running on the ClearSCADA servers on your system. The driver is represented by the SNMP Manager component in the ClearSCADA Installation Wizard’s Setup window. The component is located within the Server branch of tree that is displayed in the window (see Install a Driver in ClearSCADA in the ClearSCADA Guide to Drivers).
You may also need to specify a delay to allow local SNMP agents on the server to start up before the driver polls them for data (for instance for information on disk space, or power supply). For further information, see Configuring SNMP Server Settings.
You then define SNMP points within the ClearSCADA database to define the values that ClearSCADA is to retrieve, and how that data is handled within ClearSCADA. The SNMP driver supports four types of SNMP point, which each handle different types of data (see Configuring Points on the SNMP Driver).
Many of the point settings need to correspond to the settings of the relevant SNMP agent, or the poll requirements for the data. Some of these settings are fixed, others are configured by an engineer. You need to have access to, or an understanding of the settings used on your system before you can configure SNMP points successfully.
For instance, you need to know the IP address of the SNMP agent with which each point is associated, the community (only in SNMP v1 and v2), and the object identifier (OID) for the point value within the SNMP agent.
NOTE: We recommend the use of a free tool called Getif for discovering the correct object identifiers (OIDs) for SNMP agents. You can download the tool from http://www.wtcs.org/snmp4tpc/getif.htm.
You also need to be aware of which optional features are required for each SNMP point. These features include:
- Alarm views
- Alarm redirections
- Historic data storage
- User methods.
You can also use core ClearSCADA features with SNMP points, including Lists, Actions, and Mimics.
For actions that are specific to the SNMP driver, see Using SNMP Specific Actions. For further information on actions and for details on Lists and Mimics, see the core documentation.