Rockwell Automation 1756 ControlLogix Communication Module



Rockwell Automation 1756 ControlLogix Communication Module

Basic Information and Module Classification

1. Basic information

Document positioning: Technical manual for industrial grade ControlLogix communication module, including module selection, parameter configuration, installation requirements, suitable for building and maintaining industrial control networks;

Core coverage: 7 types of networks (EtherNet/IP, DeviceNet, DH+, Remote I/O, DH-485, SynchLink, ControlNet), 3 types of special modules (conformal coating, XT wide temperature, legacy obsolete);

Module model system: Named according to "network type+functional characteristics", such as 1756-EN2T (EtherNet/IP network, 2-port), 1756-DNB (DeviceNet network), suffix "K" represents normal coating (anti-corrosion), "XT" represents wide temperature environment (-25~70 ℃).

2. Overview of module classification

Network type, core module model, functional positioning, special version

EtherNet/IP 1756-EN2F/EN2TT/EN2TP/EN2TR/EN3TR/EN4TR/ENBT Industrial Ethernet Bridge, supporting real-time I/O and message communication 1756-EN2TK (coating), 1756-EN2TXT (wide temperature)

DeviceNet 1756-DNB/E connects the underlying network bridging of sensors/actuators-

DH+/Remote I/O 1756-DHRIO, 1756-RIO/B DH+message communication, Remote I/O scanning/adaptation 1756-DHRIOXT (wide temperature)

DH-485 1756-DH485 low-cost serial communication network-

SynchLink 1756-SyncH fiber optic synchronous communication for distributed motion control-

ControlNet 1756-CN2/CN2R/CNB/CNBR legacy control network, real-time high-throughput 1756-CN2RK (coating), 1756-CN2RXT (wide temperature)

Legacy 1756-EWEB (web server) and 1756-TIME (time synchronization) have been discontinued and alternative solutions are provided-

Core network module technical specifications (sorted by network type)

（1） EtherNet/IP module: Industrial Ethernet core

1. Core functions and selection criteria

Key capabilities: Supports CIP protocol (real-time I/O+message communication), DLR ring network (1756-EN2TR/EN3TR/EN4TR), PRP redundancy (1756-EN2TP/EN4TR, firmware 4.001+), CIP Security encryption (1756-EN4TR);

Selection Comparison Table:

Module model, port specifications, maximum number of connections (TCP/CIP), packet rate (PPS), and adaptation scenarios

1756-ENBT 1 × RJ45 (10/100Mbps) 64/128 5000 (I/O)/900 (HMI) basic Ethernet networking

1756-EN2T 1 × RJ45 (10/100Mbps) 128/256 25000 (I/O)/2000 (HMI) Medium scale I/O control

1756-EN4TR 2 × RJ45 (10/100/1000Mbps) 512/1000 (I/O)+528 (message) 50000 (unencrypted)/15000 (encrypted) large redundant network, supporting 256 axis motion

1756-EN2TXT (wide temperature) 1 × RJ45 (10/100Mbps) 128/256 25000 (I/O) Extreme temperature environment (-25~70 ℃)

2. Common technical parameters

Power supply: 5.1V DC (current 0.7~1.2A), partially supporting 24V DC auxiliary power supply;

Environmental adaptability: Operating temperature of 0-60 ℃ (conventional)/-25~70 ℃ (wide temperature), humidity of 5%~95%, non condensing, ESD resistance (contact with 6kV/air 8kV);

Certification: c-UL-us (Class I Div 2), ATEX Zone 2, CE, RCM, compliant with ODVA EtherNet/IP.

（2） DeviceNet module: underlying device networking

Core parameters: 1756-DNB/E supports 125/250/500kbps communication rate, maximum 64 nodes, 24V DC (11-25V) power supply, current 60mA;

Key features: Supports CIP protocol, adapts to sensors/actuators, USB port for temporary configuration (prohibited for use in hazardous environments);

Environment and Certification: Operating temperature range of 0-60 ℃, certified with EtherNet/IP module, compliant with ODVA DeviceNet.

（3） DH+/Remote I/O module: legacy network compatible

1756-DHRIO (dual function)

DH+function: Supports speeds of 57.6/115.2/230.4kbps, with a maximum of 32 message connections;

Remote I/O function: As a scanner, it supports 32 logical racks and 16 block transfer connections;

Parameters: 5.1V DC current 850mA, operating temperature 0~60 ℃ (conventional)/-25~70 ℃ (XT model).

2. 1756-RIO/B (Remote I/O only)

Function: Supports scanner/adapter mode, 32 physical racks, transfers analog/digital/block data;

Restriction: When used as an adapter, it must be paired with a ControlLogix controller.

（4） ControlNet module: Legacy High Throughput Network

Core parameters: Communication rate of 5Mbps, maximum 99 nodes, 1756-CN2/CN2R supports 128 Logix connections, 1756-CNB/CNBR supports 40-48 connections;

Redundancy feature: 1756-CN2R/CNBR supports dual port redundancy to ensure uninterrupted network operation;

Alternative suggestion: It is recommended to migrate to EtherNet/IP, refer to the "ControlNet to EtherNet/IP Migration Reference Manual" (CNET-RM001).

（5） Other network modules

1756 SynchLink: Fiber optic communication (650nm wavelength, 200/230 μ m HCS fiber), speed 5Mbps, high synchronization accuracy, used for multi chassis motion coordination;

1756-DH485 (DH-485): speed of 9.6/19.2kbps, 2 DB9 ports, requires a 1761-NET-AIC converter to connect to the network and adapt to old devices.

Special version and Legacy module description

1. Special version module

Conform coating version (suffix K): such as 1756-EN2TK, 1756-CN2RK, anti salt spray, corrosion, suitable for humid/chemical environments;

XT wide temperature version (suffix XT): such as 1756-EN2TXT, 1756-DHRIOXT, working temperature -25~70 ℃, in compliance with ANSI/ISA-S71.04 G1/G2/G3, suitable for extreme industrial environments.

2. Legacy module (discontinued)

1756-EWEB: discontinued in November 2021, alternative solution is 1756-CMS1B1/CMS1C1 (Compute module);

1756-TIME: discontinued in November 2021, replaced by Aparian A-TSM/B time synchronization module（ https://www.aparian.com/products/timesync ）.

Common technical requirements and supporting resources

1. General parameters

Power supply and power consumption: Most modules rely on ControlLogix chassis 5.1V DC power supply, with a power consumption of 3.5~6.7W, and some require 24V DC assistance;

Installation requirements: 1 slot width, suitable for chassis such as 1756-A4/A7/A10, recommended power supply 1756-PA75/PB75 (regular), 1756-PAXT/PBXT (XT wide temperature version);

Electromagnetic compatibility (EMC): compliant with IEC 61000-6-2/-4, resistant to radiated interference (10V/m, 80-2000MHz), and resistant to EFT (± 3kV, 5kHz).

2. Key attachments

Network Type Attachment Model Description

EtherNet/IP 1585J-M8PBJM-x Ethernet jumper (2/5/10m, Cat5e/Cat6)

DeviceNet KwikLink Lite flat cable and IDC connector, fast networking without wire stripping

ControlNet 1786-RG6 quad shielded coaxial cable, 1786-TCT2BD1 (IP67 T-connector)

DH+1770-CD Belden 9463 dual axis cable, 9300-RADKIT (remote dialing kit)

Selection and migration suggestions

Priority for new projects: prioritize the selection of EtherNet/IP modules (1756-EN4TR/EN2TR), which support redundancy, encryption, and motion control, and are compatible with future expansion;

Legacy network maintenance: DH+/ControlNet module is only used for upgrading existing systems. It is recommended to migrate to EtherNet/IP for new scenarios;

Special environment adaptation: Choose the "K" coating for humid/corrosive environments, and the "XT" wide temperature version for high and low temperature environments to ensure compliance with on-site protection levels;

Module replacement for elimination: 1756-EWEB/1756-TIME needs to be replaced according to the recommended document plan to avoid operational risks in the later stage.