The Allen-Bradley 1768-CNB, also cataloged as the 1768-CNB Communication Interface Module, operates as a dedicated hardware component for high-speed network bridging within CompactLogix 1768 controller systems.
Hardware Specifications
Parameter
Specification
Model
1768-CNB
Brand
Allen-Bradley
Origin
United States
Weight
0.28 kg (0.63 lbs)
Dimensions
Single-slot CompactLogix 1768 module footprint
Operating Temp
0 to 60 deg C
Power Consumption
5.14 W (1 A at 5 VDC backplane)
Power Dissipation
5.14 W
Thermal Dissipation
17.5 BTU/hr
Communication Rate
5 Mbps
Max Connections
48 connections
Max Nodes
99 nodes
Connectors
1 BNC ControlNet media connector, 1 RJ45 NAP connector
Isolation Voltage
30 V continuous
EtherNet/IP and ControlNet Deterministic Networks
ControlNet Deterministic Networks: Executes high-speed, repeatable control data transmission at 5 Mbps over RG-6 coaxial media, supporting up to 48 concurrent logical connections across 99 ControlNet network nodes.
I/O Density Scaling: Occupies a single slot on the 1768 backplane, allowing multi-axis motion and I/O expansion without exceeding controller power draw limits.
Firmware Flash Compatibility: Fully compatible with ControlLogix and CompactLogix 1768 backplane routines via RSLogix 5000 / Studio 5000 environment for firmware flashing and node configuration.
Frequently Asked Questions
Q: How many total logical connections can the 1768-CNB module maintain concurrently?
A: The module supports up to 48 concurrent CIP and ControlNet connections for I/O bridging, explicit messaging, and peer-to-peer data transfer.
Q: Does the 1768-CNB module support redundant ControlNet media channels?
A: No, the 1768-CNB features a single BNC media connector for non-redundant ControlNet network topologies alongside one Network Access Port (NAP).
Q: What power draw does the module place on the 1768 system backplane?
A: The module draws 1 A at 5 VDC from the backplane, resulting in a total power consumption and power dissipation rating of 5.14 W.
Field Installation Guidelines
Backplane Slot Selection: Mount the module into any available slot (slots 1 through 4) on the left side of a 1768 CompactLogix controller backplane assembly.
Coaxial BNC Termination: Connect RG-6 75-ohm coaxial cable to the front BNC jack. Install 75-ohm BNC terminators at both physical ends of the ControlNet trunk line segment.
Network Access Port (NAP): Use the RJ45 8-pin NAP interface solely for temporary programming terminal attachment and network diagnostics using a dedicated network access cable.
Enclosure Grounding: Verify the 1768 DIN rail or chassis panel mounting arrangement is bonded to a low-impedance earth ground conductor to comply with EMC immunity requirements.
