To provide proper operation of a Trap-tag, you should configure a filter (data of what traps/devices need to be written to the tag). As an example, view the SNMP Trap v1 receive setting.
If a MIB-file exists, any MIB-browser can be used to configure such a filter - for instance, iReasoning MIB Browser.
Open a MIB-file of your device, and find a required Trap in the tree.
Highlight the trap; trap properties contains all of parameters required to configure a filter.
Add a new tag to a Trap-device of the OPC server, and type parameters from the MIB-browser.
Specify an IP address of your device as well.
In the run-time mode, a value is written to the tag when appearing a message.
If required, not all of filter parameters can be configured. For example, only a filter by an IP address of a device can be specified, and all of alarm messages from a device will be received in the same tag.
It is also possible to configure using the parameters of the adopted Trap in the SCurrentTrap tag - the sequence of parameters is described in the previous topic.