History of Changes

1756-UM543S-EN-P, November 2025

Topic
Added content to the ATTENTION table in section Protect the Safety Signature
Updated the User Initiated row in the Controller Power table that explains how what happens when you insert a memory card and powerup the controller
Moved topic Trusted Slots Slots on the Controller to chapter Manage Controller Communications
Updated content in the ATTENTION table in section Develop Safety Applications
Added topic CIP Bridging Control to chapter Develop Secure Applications
Added content on how to access diagnostic assembly information

Change
Updated Additional Resources table
Revised Controller Redundancy section
Revised Secure Controller Systems section
Added IEC-62443-4-2 SL 1 security certification content for safety controllers
Added statement about impact of license-based source protection on download times
Added Privacy Aspects section
Added information about unique code for troubleshooting major faults Type 1, Codes 60, 61, 62

Change
Updated information about system compatibility and extreme environment ratings
Added catalog numbers 1756-L81ESXT, 1756-L82ESXT, 1756-L83ESXT, 1756-L84ESXT, 1756-L8SPXT, 1756‑L81E‑NSEXT, 1756-L82E-NSEXT, 1756-L83E-NSEXT, 1756-L84E-NSEXT, 1756-L85E-NSEXT, 1756-L81EPXT, 1756‑L83EPXT, and 1756-L85EPXT
Updated information about conformal coated products
Added recommended SD cards

Change
Added catalog number 1756-L85ES
Revised the Safety Signature section in Chapter 2
Updated the controller Safety tab screenshots
Updated the Safety I/O Replacements Options section
Added a statement about the status of the Enable Controller Webpages checkbox

Change
Updated the controller minimum requirements

Change
Moved information about connection reaction time limit to publication 1756-RM012
Added GuardLogix-XT™ catalog numbers
Revised ControlLogix-XT™ and GuardLogix-XT™ Controllers section
Revised information about the safety signature
Added 1756-EN4TR, 1756-EN4TRK, 1756-EN4TRXT catalog numbers
Added information about secure socket objects
Added introduction and Program Safety Applications section to Chapter 11 and moved other safety topics from Chapter 11 to publication 1756-RM012
Added information about component tracking

Change
Added publication to the Additional Resources table
Separated ControlLogix® and GuardLogix® K catalog numbers
Updated CIP Security™ content
Added CIP Security™ to ControlLogix® and GuardLogix® controller feature tables
Added CIP Security™ considerations for the number of EtherNet/IP™ nodes
Added K controllers to the description of ControlLogix® 5580 controllers that support
IEC-62443-4-2 SL 1 security requirements
Added syslog collector to controller system image
Restructured security checklists
Moved Verification of Security Implementation content to the beginning of security checklist
Changed “ Studio 5000 Logix Designer® application” checklist item in Table 37 from “yes” to “may be required” for IEC-62443-4-2 SL 1 security requirements
Added FactoryTalk® Security software to Table 38 and revised details
Revised details of “Firmware update” checklist item in Table 38
Added “Syslog collector” checklist item to Table 41
Changed “Controller log” checklist item in Table 41 to “Disabled controller log auto-write” and revised details
Added information about matching firmware revisions and Trusted® slots
Changed NVS to non-volatile controller memory
Added syslog log collector to Controller Log section
Added method to disable CIP Security™ ports in FactoryTalk® Linx software
Updated general status messages for the controller

Change
Updated link to Logix Controller and I/O Fault Codes
Updated Conformal Coated Products statement
Updated Controller Log section
Added Controller Status messages

Change
Added ControlLogix® NSE, ControlLogix-XT™ , and ControlLogix® Process controllers
Updated safety signature definition
Updated behavior of controller status indicators while loading a project from the SD card
Added Simple Network Management Protocol (SNMP).
Added Automatic Diagnostics
Added Considerations for Communication Loss Diagnostics

Change
Added links to access Controller and I/O fault code information from the Knowledgebase Support Center

Change
Moved information on Controller and I/O fault codes to the attached spreadsheets
Added Develop Secure Applications chapter
Updated Controller webpage information

Change
Updated the ControlLogix® and ControlLogix-XT™ Chassis and Slots table

Change
Changed some remaining instances of “safety task signature” to “safety signature” throughout
Updated the Assign the Safety Network Number (SNN) section
Updated the Copy and Paste a Safety Controller Safety Network Number section
Updated the Set the SNN of a Safety I/O Device section

Change
Added GuardLogix® 550 controllers and Safety Information

Change
Updated tables with new maximum number of EtherNet/IP™ nodes that are supported in Version 30 or later
Added the 1756-IF16IH module to the list of supported HART devices

Change
Added the catalog numbers 1756-L81E, 1756-L82E, 1756-L84E
Added ControlFLASH™ to the Required Software section
Added the section ‘ EtherNet/IP™ Network Communication Rates'
Added information on the Ethernet node counter to the section 'Nodes on an EtherNet/IP™ Network
Added the appendix ‘Security Options’

Change
Updated the diagram for multiple controllers in one chassis