Allen-Bradley 1756-EN2TXT XT EtherNet/IP Module for Harsh Environments

The Allen-Bradley 1756-EN2TXT is the extended-temperature, conformal-coated variant of the ControlLogix EtherNet/IP bridge module, part of Rockwell Automation’s Logix-XT harsh-environment portfolio. It installs in any standard ControlLogix chassis slot and bridges the 1756 backplane to an EtherNet/IP network, carrying real-time implicit I/O, explicit messaging, produced and consumed tags, and HMI traffic over a single 10/100 Mbps twisted-pair connection. Where the standard Allen-Bradley 1756-EN2TXT differs from the base 1756-EN2T is not in logic or feature set but in environmental hardening: the XT designation means a wider operating window, a factory-applied conformal coating, and approvals that let the module live in cabinets where salt, corrosive gases, condensation, humidity, and fungal growth would defeat ordinary electronics.The module’s capacity is substantial. It supports 256 Logix communication connections and 128 TCP/IP connections, with 128 CIP unconnected messages on the backplane side and 128 on the Ethernet side. At firmware revision 3.6 and later, paired with RSLogix 5000 version 18 or Studio 5000, the Allen-Bradley 1756-EN2TXT delivers up to 25,000 I/O packets per second and supports up to eight Integrated Motion on EtherNet/IP axes—performance that places it well ahead of the legacy 1756-ENBT and makes it suitable for motion-coordinated cells as well as ordinary distributed I/O. The front face carries a USB 1.1 full-speed port for temporary local programming and a rotary-switch arrangement for quick IP address assignment, so a rack can be brought online without BOOTP/DHCP tooling.Because it is a bridge rather than a switch, the Allen-Bradley 1756-EN2TXT connects the chassis to an external Ethernet infrastructure—star, linear, or home-run to an external switch—and does not itself form a Device Level Ring. This is the critical distinction between the -EN2TXT and the -EN2TRXT: the former is the correct choice when the network is switched externally and the priority is environmental rating; the latter is required when ring topology and single-fault tolerance must be built into the module itself. For plants standardising on ControlLogix in outdoor, coastal, mining, or chemically aggressive locations, the Allen-Bradley 1756-EN2TXT is the communication module that preserves the standard architecture without derating the enclosure or relocating the cabinet.

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Description

Technical Specifications

Parameter	Value
Product Model	1756-EN2TXT
Manufacturer	Rockwell Automation / Allen-Bradley
Product Type	ControlLogix EtherNet/IP Communication Bridge Module, XT
Network Protocol	EtherNet/IP (CIP)
Communication Rate	10/100 Mbps, auto-negotiate, half/full duplex
Ethernet Ports	1 × RJ45, Category 5e (note: single port, no embedded switch)
Logix / CIP Connections	256
TCP/IP Connections	128
CIP Unconnected Messages	128 (backplane) + 128 (Ethernet)
Backplane Current Draw	1.0 A @ 5.1V DC; 3 mA @ 24V DC
Power Dissipation	5.1 W (17.4 BTU/hr)
Isolation Voltage	30V DC continuous, basic insulation; Ethernet-to-backplane and USB-to-backplane tested at 853V AC for 60 s; USB-to-Ethernet: no isolation
USB Port	1 × USB 1.1 Type B, 12 Mbps (temporary local programming only)
Slot Width	1 (any ControlLogix chassis slot)
Chassis Compatibility	1756-A4LXT, 1756-A5XT, 1756-A7XT, 1756-A7LXT
Compatible Power Supplies	1756-PAXT, 1756-PBXT
Operating Temperature	−25°C to +70°C (−13°F to +158°F)
Surrounding Air, Maximum	70°C (158°F)
Storage Temperature	−40°C to +85°C
Relative Humidity	5% to 95%, non-condensing
Vibration	2 g @ 10–500 Hz
Shock (Operating)	30 g
Environmental Compliance	ANSI/ISA-S71.04-1985 Class G1, G2, G3
Temperature Code	T4A (North America); T4 (IEC)
Enclosure Rating	None (open style)
Certifications	UL, cUL, CE, ATEX Zone 2, IECEx, C-Tick, FM, GOST, KC, RCM, ABS, DNV, GL, LR, UKCA
Packet Rate Capacity	10,000 I/O + 2,000 HMI/MSG pps (base); 25,000 I/O pps at fw 3.6+ with L7x controller
Integrated Motion Support	Up to 8 axes on EtherNet/IP (fw 3.6+, Studio 5000 v18+)
Configuration	Studio 5000 / RSLogix 5000, RSLinx, BOOTP/DHCP utility
DLR Support	No
Weight	Approx. 0.23 kg (0.50 lb)
Warranty	1 year

Main Features and Advantages

Environmental hardening without a redesign: The XT suffix is what justifies the Allen-Bradley 1756-EN2TXT in a specification. The module operates from −25°C to +70°C, carries a factory-applied conformal coating, and is tested to ANSI/ISA-S71.04 Classes G1 through G3 for resistance to salts, corrosives, moisture and condensation, humidity, and fungal growth. A plant can therefore place the rack in an outdoor enclosure, a coastal pumphouse, or a chemically aggressive area without relocating the cabinet or derating the communication module—something that cannot be said of the standard 1756-EN2T.Capacity that removes the connection bottleneck: With 256 Logix connections and 128 TCP sessions, the Allen-Bradley 1756-EN2TXT comfortably supports a modern rack’s combination of distributed I/O, peer controller data sharing, MSG instructions, and HMI traffic. The legacy 1756-ENBT’s 64 CIP connections are routinely exhausted in a system that also runs an HMI and a few message instructions; the Allen-Bradley 1756-EN2TXT eliminates that constraint and is the usual answer when a site is troubleshooting CIP connection-timeout or connection-limit faults.Performance that reaches motion: At firmware 3.6 and later, the Allen-Bradley 1756-EN2TXT supports up to eight Integrated Motion on EtherNet/IP axes and raises the I/O packet rate to 25,000 packets per second when used with a 1756-L7x controller. This lets a single Ethernet infrastructure carry both the conventional I/O and the motion coordination, rather than requiring a separate network for the servo system.No network scheduling, no routing tables: EtherNet/IP on the Allen-Bradley 1756-EN2TXT uses standard TCP/UDP/IP encapsulation and works with ordinary commercial switches. There is no scheduled-network configuration to maintain and no routing tables to populate, which keeps commissioning and changes straightforward. Produced and consumed tags provide the controller-to-controller data sharing, while explicit messages handle the exceptional or recipe traffic.Local configuration that speeds commissioning: The USB 1.1 port provides a temporary local connection for programming and diagnostics without a permanent cable, and the rotary switches allow the IP address to be set quickly when DHCP is not available. The Allen-Bradley 1756-EN2TXT also supports SNMP (password required) and socket services, giving the IT and automation teams visibility into the module through standard network management tools.