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EventFilter

概述​

OPC UA Part 4 §7.18 EventFilter 由两部分组成:

  • SelectClauses — 抓哪些字段 (按顺序对应到事件 fields)
  • WhereClause — 过滤条件 (V1 暂未实现)

每个 SelectClause 是 SimpleAttributeOperand:

字段说明
type_definition_id事件类型 NodeId
browse_path字段路径 (list[str])
attribute_id属性 Id, 默认 VALUE
index_range数组下标 (一般 None)

不传 EventFilter 时默认抓 5 字段: EventId / EventType / SourceName / Time / Message。

代码示例​

from opcua import (
    DarraOpcUa, EventFilter, SimpleAttributeOperand, AttributeId
)

with DarraOpcUa("opc.tcp://localhost:4840") as ua:
    ua.connect()
    sub = ua.create_subscription(500)

    filter = EventFilter(select_clauses=[
        # 默认 5 字段
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["EventId"]),
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["EventType"]),
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["SourceName"]),
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["Time"]),
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["Message"]),
        # 报警特有
        SimpleAttributeOperand(type_definition_id="i=2041", browse_path=["Severity"]),
        SimpleAttributeOperand(type_definition_id="i=2782", browse_path=["ConditionId"]),
        SimpleAttributeOperand(type_definition_id="i=2915", browse_path=["ActiveState", "Id"]),
    ])

    ev = sub.subscribe_events("i=2253", filter)

    @ev.on_event_arrived
    def on_event(args):
        # fields 顺序与 select_clauses 一致
        eid = args.fields[0].as_byte_string
        time = args.fields[3].as_datetime
        msg = args.fields[4].as_string
        sev = args.fields[5].as_uint16
        active = args.fields[7].as_boolean
        print(f"[{time:%H:%M:%S}] sev={sev}: {msg} active={active}")

字段速查​

EventTypeBrowsePath含义
BaseEventType (i=2041)["EventId"]事件唯一 ID (bytes)
BaseEventType["Severity"]严重度 1-1000
ConditionType (i=2782)["ConditionId"]条件 NodeId
ConditionType["EnabledState", "Id"]bool 是否启用
AcknowledgeableConditionType (i=2881)["AckedState", "Id"]bool 是否 Ack
AlarmConditionType (i=2915)["ActiveState", "Id"]bool 是否激活
AlarmConditionType["ShelvingState", "CurrentState"]LocalizedText 屏蔽态

实现说明​

  • Stack 不支持时回退默认 5 字段并推 Diagnostic Info 事件
  • WhereClause V2 接通后支持完整 ContentFilter

最佳实践​

  • 显式列字段, 不要靠默认
  • 顺序对齐: fields[i] 顺序就是 select_clauses 顺序
  • 报警面板必抓 ConditionId
  • ActiveState 用嵌套 path: ["ActiveState", "Id"]

跨语言对照​

C#PythonJavaC++RustC
EventFilterEventFilterEventFilterEventFilterEventFilterDarraUa_EventFilter
SimpleAttributeOperandSimpleAttributeOperandSimpleAttributeOperandSimpleAttributeOperandSimpleAttributeOperandDarraUa_SimpleAttributeOperand

下一步​