艾默生Ovation DCS OPC服务分析
艾默生的OPC DA服务器，使用的ProdId为“Ovation.OPCDAServer.1”，GUID值是{A3ABA03B-6CF7-4b13-A264-FD5AA251CC76}。
OPC DA服务器版本方面，有支持OPC3.0的，也有支持OPC2.0的，影响的主要的OPC3.0支持直接读取变量值。
在OPC的浏览层次方面，采用域（节点？工作站？）、单元、站、变量、变量属性5层结果，第5层为变量的属性值，不同类型的属性值有所差别，几十到上百不等。
比如我们定义了一个Pascal001的变量，最终包含的全部OPC点和对应的点类型如下：
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],,Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],String
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Number
Pascal001.DROP1/[email protected],Integer
点的层级和浏览的节点层级刚好相反。
重点需要关注点的属性有.ED、.1W、.AV，ED是点的描述，1W的整数值，AV的模拟量的值。艾默生的数据点1W还有一个特殊写法，后面可以加":0"，表示取整数的第0位的值，这时变量实际上已经是开关量了。
OPC对应点的名称没有过多的约束，艾默生的点名称充分体现了这一点，点中可以包括很多特殊符号，如：“-”、“/”、“#”、">"、"<"、"("、")"等，路径中还有"@"符号。
点的OPC Item Properties方面，有常规的数据类型、数据值、数据质量和时戳等，也有OPC扩展的数据描述（Item Description，对应ID 101）等。
在采集数据时，可以考虑从DCS直接导出数据点的定义文件，这个方法比较简单和直接。
如果采用枚举方法，只能采用BRANCH方式，不支持FLAT方式。需要考虑他的特殊的结构带来的庞大的点名称。在艾默生中定义10万个点，浏览出来的数据点数量可能达到千万级别。