
CIP services
Chapter 1
Rockwell Automation Publication 1756-PM020F-EN-P - January 2019
17
Segment Type
Value
Byte Order Representation of Attribute ID Value (low byte first)
0
1
…
n
n+1
8-bit Attribute ID
0x30
Value
N/A
N/A
N/A
N/A
16-bit Attribute ID
0x31
00
Low
High
N/A
N/A
See also
CIP defines a way to reference items by their symbolic name. The segment
used is the ANSI Extended Symbol Segment defined in the
CIP Networks
Library, Volume 1, Appendix C
.
The Read/Write tags services can use these segments in the request path to
indicate which target tag to operate on. When addressing an arrayed tag, the
Logical Segment for Element ID is also used with the Symbolic Segment.
Segment Type
Value
Byte Order Representation (low byte first)
0
1
…
N
N+1
ANSI Extended Symbolic 0x91
Length
1st char
…
Nth Char
(1)
See also
All CIP services follow the Message Router Request/Response format
defined in the
CIP Networks Library, Volume 1, Chapter 2
. For complete
descriptions, see the
CIP Networks Library
. All
requests
take th
is
form.
Message Request Field Description
Request Service
Indicates to the object referenced in the request path to perform a task. The CIP or the
device manufacturer define these tasks. Most of the services covered in this manual are
defined by the Rockwell Automation vendor-specific objects, and are not found in the CIP
Networks Library.
Request Path Size
A byte value that indicates the number of 16-bit words in the Request Path.
Request Path
A variable sized field that consists of one or more segments. The path references the item
that services operate on in the controller. The path contains Logical or Symbolic segments
or both.
Request Data
The service-specific data that is delivered to the object referenced in the Request Path. This
field only appears in the message frame if a service has service-specific data.
This same form is used for ControlNet and EtherNet/IP communication
CIP-based networks. Requests received through the serial port use another
protocol.
Symbolic Segments
CIP Service Request/Response
Format