EtherNet/IP Network Integration Solution – Allen-Bradley 1756-EN3TR | ControlLogix Series
In modern process plants and discrete manufacturing facilities, engineers face a critical challenge: over 60% of unplanned downtime in automated production lines is traced to communication failures between PLCs, I/O subsystems, and SCADA layers. A single network interruption in a ControlLogix-based architecture can halt an entire production cell, triggering cascade faults across HMI stations, historian servers, and safety interlocks — costing facilities an average of $260,000 per hour in lost throughput (ARC Advisory Group, 2023).
The Allen-Bradley 1756-EN3TR directly addresses this vulnerability. As a dual-port EtherNet/IP bridge module for the ControlLogix platform, it enables Device Level Ring (DLR) topology — a self-healing network architecture that automatically reroutes traffic within 3ms of a link failure, eliminating single points of failure without requiring managed switches. Engineers specify the 1756-EN3TR when network uptime is non-negotiable: it bridges the ControlLogix backplane to EtherNet/IP at 100 Mbps full-duplex, supports up to 256 CIP connections, and integrates seamlessly into both new greenfield designs and brownfield upgrades of existing 1756-EN2T/EN2TR installations.
Where This Product Is Used
1. Automotive Body & Paint Assembly
In body-in-white welding cells and paint booth conveyors, the 1756-EN3TR connects ControlLogix PACs to servo drives (Kinetix 5700), vision systems (Cognex In-Sight), and robot controllers (FANUC R-30iB) over a single DLR ring. Operating in environments with ambient temperatures up to 60°C and heavy EMI from welding equipment, the module maintains deterministic cycle times ≤1ms required by ISO/TS 16949 quality systems. Typical ring size: 48 nodes across 400m of Cat6A cable.
2. Oil & Gas Pipeline SCADA
Compressor stations and metering skids use the 1756-EN3TR to bridge ControlLogix controllers to RTUs, flow computers (Emerson ROC800), and custody transfer meters over EtherNet/IP. The dual-port DLR topology satisfies API 1165 pipeline SCADA security guidelines by enabling physical network redundancy without Layer 3 routing complexity. Modules operate at -20°C to +60°C ambient, meeting Class I Division 2 panel requirements when installed in purged enclosures per NFPA 496.
3. Water & Wastewater Treatment
Municipal lift stations and WWTP aeration basins deploy the 1756-EN3TR to connect ControlLogix to VFDs (PowerFlex 755), analytical instruments (Hach sc200), and remote I/O (1734 POINT I/O) across geographically distributed sites. The module’s support for EtherNet/IP implicit messaging enables real-time DO/pH control loops at 10ms RPI, meeting EPA 40 CFR Part 503 process monitoring requirements. DLR self-healing protects against cable damage from rodents or excavation — a common failure mode in buried conduit installations.
4. Pharmaceutical & Biotech Manufacturing
FDA 21 CFR Part 11-compliant batch systems use the 1756-EN3TR to integrate ControlLogix with SCADA historians (OSIsoft PI, Wonderware), bioreactor controllers, and CIP/SIP skids. The module’s deterministic EtherNet/IP communication supports electronic batch records by timestamping process data at the controller level. Cleanroom-compatible (IP20 panel-mount), operating at 0–60°C with 5–95% RH non-condensing per GAMP 5 installation guidelines.
5. Power Generation & Utilities
Combined-cycle power plants and substations use the 1756-EN3TR to bridge ControlLogix to generator protection relays (GE Multilin 489), turbine control systems, and plant DCS (DeltaV, Ovation) via EtherNet/IP-to-Modbus TCP gateways. The module supports NERC CIP-compliant network segmentation when deployed behind industrial firewalls (Tofino, Cisco IE3400). Rated for continuous operation at 60°C ambient — critical in turbine hall environments.
6. Food & Beverage Processing
High-care zones in dairy, beverage, and meat processing facilities use the 1756-EN3TR to connect ControlLogix to hygienic servo systems, checkweighers, and X-ray inspection units over EtherNet/IP. The DLR ring topology allows network maintenance (node addition/removal) without production shutdown — essential in 24/7 continuous processing lines. Modules are installed in NEMA 4X stainless enclosures; the 1756-EN3TR itself is rated IP20 for panel interior mounting per EHEDG installation guidelines.
Technical Specifications
| Catalog Number | 1756-EN3TR |
| Series | ControlLogix (1756 platform) |
| Network Ports | 2 × RJ45 EtherNet/IP (10/100 Mbps, full-duplex) — enables DLR ring topology; both ports active simultaneously |
| Network Speed | 100 Mbps full-duplex — supports high-density I/O polling at ≤1ms RPI |
| CIP Connections | 256 concurrent — sufficient for large ControlLogix systems with 200+ I/O nodes |
| DLR Support | Yes (Ring Supervisor capable) — self-healing in <3ms; eliminates managed switch requirement |
| Backplane Current Draw | 1.0A @ 5VDC, 3.0mA @ 24VDC |
| Operating Temperature | 0°C to +60°C — covers turbine halls, outdoor panels, and process areas |
| Storage Temperature | -40°C to +85°C |
| Relative Humidity | 5–95% non-condensing |
| Enclosure Rating | IP20 (panel mount) |
| Dimensions (H×W×D) | 94.0 × 44.5 × 99.1 mm (standard 1756 single-slot) |
| Weight | Approx. 200g |
| Certifications | UL, CE, C-Tick, ATEX Zone 2 (with approved enclosure) |
| Firmware | Upgradeable via ControlFlash; compatible with Studio 5000 Logix Designer v21+ |
| Replaces | 1756-EN2TR (direct drop-in replacement, same slot footprint) |
Why Engineers Specify This Model
- In automotive welding cell applications, the 1756-EN3TR delivers sub-3ms DLR failover because its dual-port ring supervisor firmware detects link loss at the PHY layer and reroutes traffic before the controller’s RPI timeout, meeting ISO/TS 16949 cycle-time requirements.
- In oil & gas compressor station SCADA architectures, the 1756-EN3TR delivers physical network redundancy without managed switches because DLR operates at Layer 2, reducing BOM cost by eliminating redundant switch pairs and simplifying NERC CIP asset inventory.
- In pharmaceutical batch manufacturing, the 1756-EN3TR delivers deterministic timestamped process data because EtherNet/IP implicit messaging synchronizes controller and historian clocks via IEEE 1588 PTP, meeting FDA 21 CFR Part 11 electronic record requirements.
- In water treatment distributed SCADA, the 1756-EN3TR delivers resilient multi-site connectivity because its 256-connection capacity supports simultaneous polling of remote I/O, VFDs, and analytical instruments across a single ring, reducing fiber infrastructure cost by 40% vs. star topology.
- In power generation turbine control, the 1756-EN3TR delivers continuous operation at 60°C ambient because its industrial-grade components are rated for the full 1756 platform thermal envelope, meeting IEEE 1613 environmental requirements for substation equipment.
- In food & beverage 24/7 processing lines, the 1756-EN3TR delivers hot-swap node addition without ring disruption because DLR ring supervisor firmware manages node join/leave events transparently, enabling network expansion during production without a maintenance window.
Complete System Bill of Materials
The following components are typically specified alongside the 1756-EN3TR in a complete ControlLogix EtherNet/IP system:
- 1756-L85E ControlLogix Controller — Host PAC; communicates with 1756-EN3TR via backplane at 5VDC. The EN3TR bridges this controller to the EtherNet/IP network.
- 1756-PA75 Power Supply — Provides 5VDC/24VDC backplane power; must supply ≥1.0A @ 5VDC for the EN3TR slot.
- 1756-A10 Chassis (10-slot) — Houses controller, EN3TR, and I/O modules in a single backplane assembly.
- 1734-AENT POINT I/O EtherNet/IP Adapter — Remote I/O node on the DLR ring; the EN3TR manages CIP connections to each adapter.
- PowerFlex 755 VFD (20G series) — Motor drive with embedded EtherNet/IP port; connects as a DLR ring node controlled by the EN3TR.
- Stratix 5400 Industrial Switch — Optional: used in linear/star topologies or as a DLR-to-star boundary switch for legacy device integration.
- 1585J-M8CBJM-2 EtherNet/IP Cable — Rockwell-specified Cat5e industrial cable for DLR ring wiring between EN3TR ports and ring nodes.
- ControlFlash Plus Software — Required for 1756-EN3TR firmware upgrades; included with Studio 5000 subscription.
- Studio 5000 Logix Designer v21+ — Engineering software for EN3TR configuration, connection management, and DLR ring diagnostics.
Compliance & Industry Standards
- UL 508 (UL, USA) — Industrial Control Equipment listing; confirms the module meets North American electrical safety requirements for panel installation. Buyers: required for UL-labeled control panels in the US and Canada.
- CE Marking / EN 61131-2 (European Commission) — Confirms compliance with EU Low Voltage and EMC Directives for programmable controllers. Buyers: mandatory for equipment sold or installed within the European Economic Area.
- IEC 61158 / EtherNet/IP (ODVA) — Confirms conformance to the EtherNet/IP industrial protocol standard. Buyers: guarantees interoperability with any ODVA-certified EtherNet/IP device from any vendor.
- ATEX Category 3G / Zone 2 (ATEX Notified Body) — Permits installation in panels located in Zone 2 hazardous areas (gas) when using an approved Ex e enclosure. Buyers: required for oil & gas, chemical, and petrochemical applications in Europe.
- C-Tick / RCM (ACMA, Australia) — EMC compliance mark for the Australian and New Zealand markets. Buyers: required for import and installation in AU/NZ facilities.
- ODVA EtherNet/IP Conformance Tested (ODVA) — Third-party tested for CIP protocol conformance. Buyers: reduces integration risk when connecting to multi-vendor EtherNet/IP networks.
Quality Assurance & Sourcing
Sourcing Channels: Konmask.com sources the 1756-EN3TR through authorized Allen-Bradley distributors, certified surplus channels with full traceability, and direct OEM returns with factory documentation. All units are inspected before shipment.
4-Step Inspection Process:
- Visual & Physical Inspection — Enclosure integrity, connector pin condition, label authenticity, and firmware version verification against Rockwell Automation published release notes.
- Functional Power-On Test — Module seated in a 1756 chassis, powered, and confirmed to enumerate correctly in Studio 5000 with expected diagnostic LEDs (OK, NET, LNK1, LNK2).
- EtherNet/IP Communication Test — DLR ring established with two test nodes; implicit and explicit messaging verified at 1ms RPI over 30-minute soak test.
- Documentation Package Assembly — Serial number recorded, test results logged, and shipping documentation prepared.
Available Documentation: Certificate of conformance, inspection test report, firmware version record, original Rockwell Automation datasheet (Pub. 1756-TD001), and commercial invoice with HS code 8537.10.
How to Source This Part
- Submit Your Inquiry — Contact us via the product page, email support@konmask.com, or WhatsApp +0086 19859288691 with your required quantity, delivery location, and any documentation requirements.
- Receive Quote & Availability Confirmation — Our team responds within 24 hours with pricing, lead time, stock status, and available documentation. Urgent requirements (same-day quote) are accommodated for stocked items.
- Order, Inspect & Ship — Upon order confirmation, units undergo final inspection and are shipped via DHL Express, FedEx International Priority, or sea freight (for bulk orders). We ship globally to 80+ countries with full export documentation including commercial invoice, packing list, and certificate of origin.
Application-Specific FAQ
Q: Can the 1756-EN3TR replace a 1756-EN2TR in an existing DLR ring without reconfiguring the network?
A: Yes. The 1756-EN3TR is a direct drop-in replacement for the 1756-EN2TR in the same chassis slot. It uses the same EtherNet/IP port configuration and DLR ring supervisor settings. After swapping the module, update the firmware via ControlFlash and verify the module’s IP address in Studio 5000 — no ring reconfiguration is required. This makes it the preferred upgrade path for aging EN2TR installations in automotive and food & beverage lines.
Q: In an oil & gas SCADA application, how many RTUs or flow computers can the 1756-EN3TR support on a single DLR ring?
A: The 1756-EN3TR supports up to 256 concurrent CIP connections, which in a typical pipeline SCADA application translates to 50–80 RTU/flow computer nodes (each consuming 3–5 connections for I/O, diagnostics, and time sync). For larger systems, multiple EN3TR modules can be deployed in the same chassis — each managing an independent DLR ring segment — with the ControlLogix controller bridging data between rings via the backplane.
Q: Does the 1756-EN3TR support IEEE 1588 Precision Time Protocol (PTP) for pharmaceutical batch record timestamping?
A: Yes. The 1756-EN3TR supports CIP Sync (based on IEEE 1588 PTP), which synchronizes the ControlLogix system clock to a grandmaster clock on the EtherNet/IP network with accuracy better than 1 microsecond. This is the mechanism used by OSIsoft PI and Wonderware historians to timestamp batch events at the controller level — a key requirement for FDA 21 CFR Part 11 electronic batch records in pharmaceutical and biotech manufacturing.
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