A tag of the SNMP protocol is charged with data reception from a SNMP device or data writing to a SNMP device. While interrogating, the functions GetRequest and SetRequest are used.
To add a tag to a device or to a group, the 'Add. Protocol Tag' command is used:
The main settings of a SNMP tag:
•Address OID – OID of the parameter requested. OID can be known from the device documentation or from the MIB file delivered by a device manufacturer. Special browsers are used to view a MIB file – for example, iReasoning MIB Browser .
•Table element - enabling this setting means that the tag is in the table.
•Table OID - OID of the table in which the element is located.
Note. Setting the Table element is intended for cases when polling a table through a direct OID call does not work. In this case, you need to enable the setting, specify the OID of the table in which the element is located, and set the Address OID element in this table.
•Data type in server – data type of the tag
•Access type – this parameter defines what method a tag uses for interaction with a variable: ReadOnly – the GetRequest method, WriteOnly – the SetRequest method, ReadWrite – the GetRequest and SetRequest methods.
Other tag parameters are standard ones (see The Dialog of Tag Parameters ).
In addition, the OPC server is supplied with the utility of tag import from MIB-files, see the section SNMP. Tag Import