Reference · built on requestConnectorPLC, SCADA & MES

Allen-Bradley Logix 5000

Controller tags, structures, and tag lists from ControlLogix and CompactLogix controllers over EtherNet/IP CIP services.

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About

Logix 5000 is the controller family behind Rockwell Automation's ControlLogix, GuardLogix, CompactLogix, and SoftLogix lines. The Logix 5000 Controllers Data Access manual (1756-PM020) documents the vendor-specific CIP services a client uses to read and write tags over EtherNet/IP: Read Tag (0x4c), Read Tag Fragmented (0x52), Write Tag (0x4d), Write Tag Fragmented (0x53), and Read Modify Write Tag (0x4e). Tags are addressed by name through symbolic segments or, in version 21 and later, by Symbol Instance ID.

An operator on Fibric reads controller-scope tags and user-defined structures from a line, watches counters and fault words, and proposes a tag write for your approval. Each write is one CIP service and leaves a receipt: what changed, why, and how to undo it.

This is a reference listing. It documents what Fibric would read from Allen-Bradley Logix 5000 and what it could propose, based on the vendor's published interfaces. Fibric builds it under a managed deployment when you request it; selecting it here installs nothing.

What it reads

  • Controller-scope tag values through the Read Tag and Read Tag Fragmented services, addressed by symbolic name or Symbol Instance ID
  • The controller's tag list, retrieved from Symbol object instances (Class ID 0x6B) with Get_Attribute_List and paged across packets
  • User-defined structure layouts from Template object instances (Class ID 0x6C), including member names, offsets, and data types
  • Change indicators on the controller object (class 0xAC attributes 1, 2, 3, 4, and 10) that signal when tags or UDTs changed
  • Whole structures and arrays read in one pass, with atomic values typed as BOOL, SINT, INT, DINT, LINT, REAL, or DWORD

Proposed actions

  • Target capability: propose a value for a controller-scope tag through the Write Tag service (0x4d), typed by the tag type parameter
  • Target capability: propose a masked bit change on an integer tag through the Read Modify Write Tag service (0x4e)
  • Target capability: propose a batch of reads and writes grouped in one Multiple Service Packet (0x0a) so they land together

Proposed actions are target capabilities. Every action runs propose-first and needs a validated deployment and the appropriate permissions.

What you can build

  • Catch a stalled line from its own counters

    Read part counters and state DINTs on a cycle, notice when a count stops moving inside a running state, and open a downtime record for your review.

    With Line Downtime

  • Watch cycle time drift on one machine

    Read a cycle timer's accumulated value each cycle, compare it with its baseline, and flag drift before it shows up in throughput.

    With Cycle Drift

  • Queue a maintenance proposal from fault words

    Read fault and warning words from a drive or machine UDT, map bits to known faults, and propose a work order in your CMMS.

    With Predictive Maintenance

  • Change a setpoint with a receipt

    Propose a Write Tag to a recipe or setpoint DINT, show the current and new value, and record who approved it and how to reverse it.

    With Changeover Plan

What it needs

  • A ControlLogix, GuardLogix, CompactLogix, or SoftLogix controller reachable over EtherNet/IP from where the connector runs
  • Tags you want read set to External Access Read Only or Read/Write; tags set to None are invisible to outside clients
  • Logix Designer version 21 or later if you want Symbol Instance addressing for large tag counts
  • A path through any intervening switches and firewalls for CIP explicit messaging to the controller
Authentication
No credential in the protocol itself: access is governed per tag by the External Access attribute (Read/Write, Read Only, None) set in Studio 5000 Logix Designer, and by network reach to the controller.

Limits

  • A single packet carries roughly 500 bytes; larger tags need the fragmented services and a series of requests
  • Program-scope tags are not directly addressable; the manual has them copied to controller-scope tags first
  • Tag names run up to 40 characters, and longer names cost packet space and parsing time in the controller
  • When CPU Lock is on, controller memory cannot be altered and the change-detection request returns General Status 0x10, Device State Conflict

Access and pricing

Reference listing. Fibric builds the connector under a managed deployment when you request it. Your quote covers the build, capabilities, usage, and support.

Request Allen-Bradley Logix 5000

Questions and answers

Which CIP services does the connector use to read and write Logix tags?
The five vendor-specific services in the Logix 5000 Data Access manual: Read Tag (0x4c), Read Tag Fragmented (0x52), Write Tag (0x4d), Write Tag Fragmented (0x53), and Read Modify Write Tag (0x4e). Several requests can be grouped in one Multiple Service Packet (0x0a). Rockwell recommends connected messaging where possible.
How does the connector discover which tags exist?
It walks Symbol object instances (Class ID 0x6B) with Get_Attribute_List, paging because one packet cannot return every instance, then reads Template object instances (Class ID 0x6C) to learn each structure's members. It re-reads controller object attributes to notice when the program changed.
Can a tag be hidden from the connector?
Yes. In Logix Designer version 21 and later, each tag carries an External Access attribute: Read/Write, Read Only, or None. Tags set to None are absent from the symbol list and cannot be read or written from outside the controller. Logix Designer itself keeps full access.
Ask about Allen-Bradley Logix 5000

Ask about the capabilities and requirements in this listing.

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This connector listing is developed, published, and supported by Fibric. It describes integration with Allen-Bradley Logix 5000 through published interfaces. Third-party names and logos identify the systems an integration connects to; they are the property of their respective owners, who are not affiliated with Fibric and do not sponsor or endorse this listing. Trademark policy