well_known_nodes

well_known_nodes 模块预定义 OPC Foundation 标准节点的 NodeId 字符串常量. 用它代替手写 i=2258 提升代码可读性.

from darra_opcua import well_known_nodes as wkn   # 短别名
# 或
from darra_opcua import wkn                        # 已经预定义的别名

配套

• 命名空间反查见 Namespaces.
• 通过 NodeId 读取数据见 read / write.

常用根节点

常量	NodeId	含义
wkn.ROOT_FOLDER	i=84	Address Space 根
wkn.OBJECTS_FOLDER	i=85	业务数据根
wkn.TYPES_FOLDER	i=86	类型定义根
wkn.VIEWS_FOLDER	i=87	视图根
wkn.SERVER	i=2253	Server 自身对象

Server 状态

常量	NodeId	含义
wkn.SERVER_SERVER_STATUS	i=2256	Server 状态结构
wkn.SERVER_SERVER_STATUS_STATE	i=2259	状态 (Running / Failed / ...)
wkn.SERVER_SERVER_STATUS_CURRENT_TIME	i=2258	服务端当前时间
wkn.SERVER_SERVER_STATUS_START_TIME	i=2257	服务端启动时间
wkn.SERVER_SERVER_STATUS_BUILD_INFO	i=2260	BuildInfo (产品 / 厂商 / 版本)
wkn.SERVER_SERVER_ARRAY	i=2254	ServerArray 字符串数组
wkn.SERVER_NAMESPACE_ARRAY	i=2255	NamespaceArray 字符串数组

标准 ReferenceType

常量	NodeId
wkn.HAS_COMPONENT	i=47
wkn.HAS_PROPERTY	i=46
wkn.ORGANIZES	i=35
wkn.HAS_TYPE_DEFINITION	i=40
wkn.REFERENCES	i=31
wkn.HIERARCHICAL_REFERENCES	i=33

常见 DataType

常量	NodeId
wkn.BOOLEAN	i=1
wkn.INT32	i=6
wkn.UINT32	i=7
wkn.INT64	i=8
wkn.FLOAT	i=10
wkn.DOUBLE	i=11
wkn.STRING	i=12
wkn.DATE_TIME	i=13
wkn.BYTE_STRING	i=15

WellKnownNamespaces

from darra_opcua import WellKnownNamespaces

WellKnownNamespaces.OPC_FOUNDATION   # "http://opcfoundation.org/UA/"
WellKnownNamespaces.DI               # "http://opcfoundation.org/UA/DI/"

---

用法

from darra_opcua import wkn

# 不推荐: 硬编码
with ua.read("i=2258") as dv:
    print(dv.value)

# 推荐: 用常量
with ua.read(wkn.SERVER_SERVER_STATUS_CURRENT_TIME) as dv:
    print(dv.value)

---

ServerStatus 完整读取 (批量)

from darra_opcua import wkn, AttributeId

nodes = [
    wkn.SERVER_SERVER_STATUS_STATE,
    wkn.SERVER_SERVER_STATUS_CURRENT_TIME,
    wkn.SERVER_SERVER_STATUS_START_TIME,
    wkn.SERVER_NAMESPACE_ARRAY,
]
results = ua.read_many(nodes)

names = ["State", "CurrentTime", "StartTime", "Namespaces"]
for name, dv in zip(names, results):
    if dv:
        with dv:
            print(f"{name:13s} = {dv.value}")

完整列表

源码里查 darra_opcua/well_known_nodes.py 有 30+ 常量, OPC Foundation 标准命名空间下的节点都在.

下一步

• OpcUaVariant
• OpcUaDataValue