Introduction
For decades, industrial automation has evolved from hardwired relay panels to networked control architectures. The Allen-Bradley 1756-ENBT ControlLogix EtherNet/IP Bridge Module represents a key step in that evolution, letting engineers move large volumes of data over a single Ethernet backbone. This module connects ControlLogix chassis to an EtherNet/IP network, supporting distributed I/O, high-speed processor interlocking, and data collection across the plant floor.
What Is the 1756-ENBT?
The 1756-ENBT is an Allen-Bradley communication module in the ControlLogix series. It acts as an EtherNet/IP bridge, transferring data between the backplane and an Ethernet network. With one RJ45 port and one USB 1.1 configuration port, it supports 10/100 Mbps transmission in half or full duplex mode. The module handles a maximum of 64 TCP/IP connections and 128 Logix connections for I/O and information. It also supports 64 + 64 CIP unconnected messages (backplane + Ethernet) and up to 32 multicast tags. Unicast is available in RSLogix 5000 software version 16.03.00 or later. Socket services and SNMP support (password required) are included, along with duplicate IP detection starting in revision 3.3. Packet rate capacity reaches 500 pps for I/O and 900 pps for HMI/MSG traffic.
Technical Specifications
| Specification | Value |
|---|---|
| Module Type | Ethernet Communication Module |
| Series | ControlLogix |
| Ethernet-IP Communication Rate | 10/100 Mbps |
| Integrated Ports | One (1) RJ45; One (1) USB 1.1 |
| Current Draw (5.1 Volt DC) | 700 milliamps |
| Current Draw (24 Volt DC) | 3 milliamps |
| Insulation Voltage | 30 Volts Continuous |
| Power Dissipation | 3.7 W |
| Thermal Dissipation | 12.6 BTU/hr |
| Operating Temperature | 32 to 140 degrees Fahrenheit (0 to 60 degrees Celsius) |
| Enclosure | Open |
| Location | Chassis (any slot) |
| Slot Width | 1 |
| UPC | 10612598269485 |
| UNSPSC | 32151705 |
Why It Matters for Your Operation
The 1756-ENBT helps simplify network architecture. By using EtherNet/IP as a backbone, you can control, configure, and collect data from multiple devices without adding separate networks. This reduces maintenance and support costs. The module is web-enabled, so you can view settings and internal diagnostics—such as IP traffic, TCP, UDP, collision histogram, and connection management—through a standard web browser. You can also check module revision, IP address, subnet, gateway, Ethernet address, module uptime, vendor, code information, diagnostic information, name server, boot status, 1756-L1 processor mode information, and network storm information.
Applications and Integration
This module fits a range of industrial scenarios. In a manufacturing plant, it can route data between a ControlLogix controller and remote I/O chassis, enabling distributed control. In a process facility, it can connect to HMIs and engineering workstations for real-time monitoring. The 1756-ENBT also works as a Remote I/O Adapter when placed in a remote I/O chassis, allowing you to collect and configure data and remotely control ControlLogix modules, including input, output, analog, or specialty modules. It is backwards compatible with earlier systems, making it a practical choice for upgrades.
Installation and Setup
Install the 1756-ENBT in any slot of a ControlLogix chassis. It occupies one slot. Connect the RJ45 port to your Ethernet network using standard twisted-pair cabling. Use the USB 1.1 port for configuration. The module does not have rotary switches, so you set network parameters through software. Only linear topology is supported because the module has a single Ethernet port. For detailed wiring and configuration steps, follow the manufacturer’s instructions.
Maintenance and Reliability
Inspect the module periodically for secure connections and clean airflow. The open enclosure requires a clean environment to prevent dust buildup. Operating temperature ranges from 32 to 140 degrees Fahrenheit (0 to 60 degrees Celsius), so ensure the cabinet stays within that range. The 1756-ENBT draws 700 milliamps at 5.1 Volts DC and 3 milliamps at 24 Volts DC, with power dissipation of 3.7 W and thermal dissipation of 12.6 BTU/hr. These values help you plan power and cooling. For safety, always follow the manufacturer’s safety manual and do not attempt internal repairs.
Selection Guide
Before buying a 1756-ENBT, verify your network requirements: 10/100 Mbps speed, 64 TCP/IP connections, and 128 Logix connections. Check that your chassis has an available slot. Confirm compatibility with your RSLogix 5000 software version, especially if you need unicast. SpareTechPLC is a reliable supplier for this module. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
FAQs
Q: What is the maximum number of TCP/IP connections supported by the 1756-ENBT?
A: The module supports a maximum of 64 TCP/IP connections.
Q: Can I use the 1756-ENBT in a remote I/O chassis?
A: Yes, it can act as a Remote I/O Adapter when placed in a remote I/O chassis.
Q: What software version is required for unicast support?
A: Unicast is available in RSLogix 5000 software version 16.03.00 or later.
Q: Does the 1756-ENBT have rotary switches?
A: No, the 1756-ENBT does not have rotary switches.
Q: What is the power dissipation of the 1756-ENBT?
A: Power dissipation is 3.7 W, with thermal dissipation of 12.6 BTU/hr.
