Rockwell Automation Allen-Bradley Logix 5000 Series User Manual

CIP services
Chapter 1
Rockwell Automation Publication 1756-PM020F-EN-P - January 2019 19
• Read Modify Write Tag Service (0x4e)
The first four services preceding can be used with two addressing methods:
• Symbolic Segment Addressing
• Symbol Instance Addressing (available in version 21 and later.)
This table describes the addressing methods.
Addressing Method How it Works When to Use
Symbolic Segment
•
Uses the name of the tag in an ASCII format using ANSI
Extended Symbolic Segments
• Allows direct access to the tags as displayed in the
Logix Designer application Data Monitor
• The number of characters in the name affects:
• Packet size
• The number of services that can fit in the
Multiple Service Packet service
• The parsing time of the incoming message in
the controller
•
For best performance in applications that access small to
moderate amounts of data.
• For improving performance by organizing the data into
user-defined structures and accessing those structures.
Symbol Instance
• Uses the instance ID of the symbol class for the tag you
want to access.
• The client application that accesses the controller
must:
• Retrieve the symbol instance information
from the controller to associate the name
of the tag with its instance ID
• Use the instance ID to access the tag.
For best performance in applications that access a large
number of tags.
Also use the Multiple Service Packet Service (0x0a) to combine multiple
requests in one message frame. This improves performance when accessing
many tags by minimizing the time to transmit and process multiple packets.
The number of requests that are included is limited by the size of each
request. This depends on the content of the request. For example, the number
of characters in the tag names impacts the number of requests combined by
the Multiple Service Packet Service. For further information, see Multiple
Service Packet Service.
These services have more descriptive names than earlier versions of this
publication.
Service Service name in earlier versions of this manual, Service name in Logix Designer
Read Tag Service CIP Read Data CIP Data Table Read
Read Tag Fragmented Service Read Data Fragmented Format N/A
Write Tag Service CIP Write Data CIP Data Table Write
Write Tag Fragmented Service Write Data Fragmented Format N/A

Rockwell Automation Allen-Bradley Logix 5000 Series Specifications

General

Brand	Rockwell Automation
Model	Allen-Bradley Logix 5000 Series
Category	Controller
Language	English