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8 CIP Message Communications
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
8-4 Specifying Request Path
8
8-4-1 Examples of CIP Object Specifications
8-4 Specifying Request Path
The CIP object, variable name, structure member name, and array index are specified for the request
path. In CIP, the EPATH data type is used for the request path. With this method, the request path is
divided into segments and a value is assigned to each segment. The request path notation shows the
path to the final destination when the data segments are joined together. Each segment includes the
segment type information and the segment data.
The first byte gives the interpretation method for the segment. It consists of two parts; a 3-bit segment
type and a 5-bit segment format.
The segment type specifications are defined as follows in the CIP specifications.
The specifications of segment format are different for each segment type. Use the segment format to
request a service from a particular object of a particular device. Logical segments and data segments,
which are needed to specify variables in CIP message communications, are described below.
Logical Segments are joined to form the request path that specifies the object to access.
Segments are joined to form the request path that specifies the variable to access.
Segment Type
Meaning
7 6 5
0 0 0 Port Segment
0 0 1 Logical Segment
0 1 0 Network Segment
0 1 1 Symbolic Segment
1 0 0 Data Segment
101Data Type
110Data Type
111Reserved
8-4-1 Examples of CIP Object Specifications
8-4-2 Examples of Variable Specifications
Segment 1 Segment 2 Segment 3 Segment 4
Segment Type Segment Format
7 6 5 4 3 2 1 0
Logical Segment
(Attribute ID)
Logical Segment
(Instance ID)
Logical Segment
(Class ID)
Specify the Class ID. Specify the Instance ID. Specify the Attribute ID.
Data Segment
Logical Segment
(Member ID)(ANSI Extended Symbol Segment)
Specify the variable name and
the member name.
Specify the array index.
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