最近在學習EtherNET/IP，PATH不太明白，翻了翻規(guī)范，在這里記個筆記。下面的敘述可能是中英混合，有一些是規(guī)范中的原文我直接搬過來的。我翻譯的不準確。

Segment

PATH是CIP Segment中的一個分類。要了解PATH先要了解Segment

參考規(guī)范卷1，附錄C-1
A CIP segment is a stream of encoded items used to reference, describe, and/or configure a specific CIP entity。

CIP Segment 分類如下
? Port segment – used for routing from one subnet to another
? Logical segment - logical reference information (such as class/instance/attribute IDs)
? Network segment - specifies network parameters needed to transmit on some networks
? Symbolic segment - symbolic name
? Data segment - embedded data (such as configuration data)

Segment使用一個字節(jié)編碼，包含Segment類型和格式。格式根據(jù)Segment類型不同而不同

PATH

PATH屬于其中的Logical segment.
一個PATH包含多個Logical segment，在一個object中引用其他object的類，實例，屬性。

PATH用途如下
? In Connection and Connection Manager Objects, paths indicate the object(s) to/from which
I/O data is moved.
? In Assembly Objects, paths indicate the attributes in other objects which are used to form
the assembled I/O data.
? In Parameter Objects, paths indicate the actual attribute in another object which is being
described by the Parameter Object.

PATH結構如下，需要注意的是，這里的PATH只有一個段屬性，PATH可以包含多個段屬性，訪問到更深入的數(shù)據(jù)。后面會給例子。

logical segment 編碼如下

舉例

舉三個例子

• 8-Bit Service ID Segment (0x38)
• Electronic Key Segment (0x34)（The Electronic Key segment shall be used to verify/identify a device）
•