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Bulletin 1756 ControlLogix Programmable Automation Controller Communications

ControlLogix Communications

The ControlLogix® Communication Modules support EtherNet/IP™, ControlNet™, DeviceNet™, Data Highway Plus™, Remote I/O, Foundation Fieldbus, serial, DH-485 and SynchLink™ networks. Interface using ControlLogix communication modules via a ControlLogix gateway (without a controller in the gateway chassis), or interface directly to a ControlLogix controller. ControlLogix extreme environment communication modules are available for EtherNet/IP, ControlNet, Data Highway Plus and Remote I/O networks.

  • Overview
  • Product Selection
  • Specifications
  • Software
  • Documentation
  • Resources


  • Multiple communication modules in a single ControlLogix® backplane can bridge or route data between different networks
  • Lets you route a message through a maximum of four chassis (eight communication hops)
  • Does not require a ControlLogix controller in the chassis

1756 EtherNet/IP™ Communication Interfaces:

  • 128 Logix connections (1756-ENBT and 1756-EWEB) or 256 Logix connections (all other modules)
  • Embedded switch technology (1756-EN2TR, 1756-EN3TR, and 1756-EN2TRXT)
  • Extreme environment support via ControlLogix-XT™ communication modules (1756-EN2TXT and 1756-EN2TRXT)
  • Secure connectivity from the control system to upper level systems, programming terminals, and other ControlLogix controllers using the secure communications module (1756-EN2TSC)

1756 DeviceNet™ Communication Interfaces

  • Supports 64 nodes

1756 ControlNet™ Communication Interfaces

  • 64 Logix connections (1756-CNB and 1756-CNBR) or 128 Logix connections (all other modules)
  • Supports 99 nodes
  • Supports redundant media (1756-CN2R, 1756-CNBR and 1756-CN2RXT)
  • Extreme environment support via ControlLogix-XT communication module (1756-CN2RXT)

1756 Data Highway Plus™ and Remote I/O Communication Interfaces

  • 32 Logix connections (1756-DHRIO and 1756-DHRIOXT)
  • Data Highway Plus and Remote I/O module (1756-DHRIO) supports messaging between devices on DH+™ network
  • Remote I/O module (1756-RIO) acts as scanner or adapter on a remote I/O network
  • Extreme environment support via ControlLogix-XT communication module (1756-DHRIOXT)

1757 FOUNDATION Fieldbus Linking Devices

  • Bridges from either an Ethernet network or a ControlNet network
  • 16 devices per H1 link (8...10 devices recommended)
  • 32 devices (1757-FFLD2 and 1757-FFLDC2) or 64 devices (1757-FFLD4 and 1757-FFLDC4) per linking device

1756 SynchLink™ Communication Interfaces

  • Time-synchronization and data broadcasting for distributed motion and coordinated drive control
  • Moves a limited amount of data from one chassis to another at high speed
  • Lets one controller consume motion axes data from a controller in another chassis

Additional Information

Rockwell Automation Integrated Architecture Solutions provide the foundation to drive plantwide optimization efficiently and effectively, enabling you to respond competitively to the economy and changes in consumer demand.

Our Extreme Environment (XT) system [PDF] includes control, communication, and distributed I/O products that extend the benefits of the Rockwell Automation Integrated Architecture™ to applications with more demanding environmental conditions.


ControlLogix Communication Modules Specifications Technical Data1756-TD003


All Modules

  • c-UL-us
  • CE
  • CSA
  • C-Tick
  • FM
  • ATEX
  • TÜV

EtherNet/IP Modules

  • ODVA-EtherNet/IP

DeviceNet Modules

  • ODVA

ControlNet Modules

  • CI

Certifications apply when product is marked. See our Product Certification site for Declarations of Conformity, certificates and other certification details.

Looking for Additional Information?

To find additional product information (CAD drawing files, 3D models, etc.) enter the complete catalog number (including dashes) below.


Use RSLogix 5000 programming software (L6 models) or the Studio 5000 Logix Designer software (L7 models) from Rockwell Software® to design and configure your ControlLogix® or GuardLogix® system.

The controllers and modules you select, along with your network configuration, determine what additional software packages you need to configure and program your system. Additional required software may include RSNetWorx configuration software and RSLinx communication software.

Learn More

Additional software products are available from Rockwell Software.


Integrated Architecture BrochureIA-BR005
ControlLogix Selection Guide1756-SG001
NetLinx Selection GuideNETS-SG001
ControlLogix Communication Modules Specifications Technical Data1756-TD003
EtherNet/IP Modules in Logix5000 Control Systems User ManualENET-UM001
ControlNet Modules in Logix5000 Control Systems User ManualCNET-UM001
DeviceNet Modules in Logix5000 Control Systems User ManualDNET-UM004
ControlLogix System User Manual1756-UM001
EtherNet/IP Embedded Switch Technology Application GuideENET-AP005
More ControlLogix publications in Literature LibraryAll Languages

Can’t Find What You Need?

Browse our Literature Library where you can search for additional publications in more languages. You can also use the Advanced Search feature to search by catalog number, publication type, title, or keywords to narrow your results.

Product Certifications

See our Product Certification site for Declarations of Conformity, certificates and other certification details.

Configuration & Selection Tools

Other Resources

  • Knowledgebase — Visit our online resource for technical information, support chat and forums, software updates, and product safety advisories/notices.