The 1768-CNB module serves as a dedicated ControlNet network interface for the CompactLogix controller family. Manufactured by Allen-Bradley, this module enables seamless communication between controllers, I/O devices, and HMIs over a ControlNet backbone. It supports up to 48 simultaneous connections, making it suitable for medium to large control architectures. Additionally, the 1768-CNB module handles up to 99 nodes on a single network, offering excellent scalability for growing facilities.
This interface module operates at a fixed network communication rate of 5 Mbps, ensuring stable and deterministic data transfer. Its built-in media redundancy feature allows for non-redundant BNC media operation, while the NAP (Network Access Port) provides a convenient RJ45 shielded connector for temporary programming access. Therefore, engineers can easily troubleshoot or configure the network without disrupting normal operations.
The 1768-CNB module draws 1 ampere at 5 volts from the backplane and dissipates 5.14 watts of power. Its thermal output reaches 17.5 BTU/hr, which remains manageable within standard enclosure environments. Furthermore, this module occupies only one slot in a 1768 chassis, leaving room for other I/O or processor modules. Users can mount it via DIN rail or panel attachment, offering flexible installation options.
Network and Communication
The 1768-CNB supports ControlNet as its primary communication protocol. It delivers a fixed baud rate of 5 Mbps, which guarantees synchronized data exchange among all connected nodes. With a maximum of 48 connections, this module can handle complex logic coordination and real-time data sharing. Additionally, it supports up to 99 nodes, allowing users to build distributed control systems with multiple devices spread across large areas.
This module includes two physical connectors: one BNC connector for standard non-redundant media, and one NAP connector (RJ45, 8-pin with shielding). The NAP port provides temporary access for programming laptops or maintenance tools. Consequently, technicians can monitor network performance or update firmware without unplugging operational cables.
Electrical and Power Ratings
The 1768-CNB draws a backplane current of 1 A at 5 V DC. Its total power consumption is rated at 5.14 W, and it dissipates the same amount as heat. Thermal dissipation is specified at 17.5 BTU/hr, which helps system integrators calculate enclosure cooling requirements. Moreover, the module provides isolation up to 30 volts, protecting sensitive components from voltage spikes or ground loops.
Environmental and Mechanical Limits
This module operates reliably within a temperature range of 0 to 60 °C. When not powered, it can withstand extremes from –40 to 85 °C. Relative humidity between 5% and 95% (non-condensing) is acceptable for most industrial settings. In terms of vibration, the 1768-CNB tolerates 5 g at 10 to 500 Hz. It also withstands operating shocks of 30 g and non-operating shocks of 50 g. These rugged specifications make it suitable for harsh factory floors and outdoor enclosures.
Physical Dimensions and Weight
The module measures 132 mm in height, 56.7 mm in width, and 105.1 mm in depth. Its approximate weight is 0.260 kg (0.57 lb). When packaged for shipping, the gross weight increases to about 0.45 kg. The compact footprint saves panel space, while the lightweight design simplifies handling during installation.
Mounting Options
You can mount the 1768-CNB module either on a DIN rail or using panel-mounting brackets. Both methods provide secure attachment within a 1768 chassis. First, align the module with the chassis backplane connector. Next, gently push it into place until the locking mechanism clicks. Finally, secure the module using the retaining screws if panel mounting is preferred.
Cable Connections
For non-redundant media operation, connect the ControlNet trunk cable to the BNC connector. Ensure proper termination resistors are installed at both ends of the trunk line. For temporary programming or diagnostic access, plug an Ethernet-style cable into the NAP port (RJ45 shielded connector). Remember that the NAP port does not support full ControlNet trunk functionality—it is intended for maintenance purposes only.
Power-Up Sequence
After installing the 1768-CNB, power up the chassis. The module will perform a self-test, and the status LEDs will indicate healthy operation. A steady green LED confirms that the module has established communication with the network. If the LED flashes red or amber, check cable connections and node addressing. Additionally, verify that the baud rate matches other ControlNet devices on the same network.
1768-CNB Communication Module (1 unit)
DIN rail mounting clip (pre-installed)
Panel mounting bracket kit (screws and washers)
Quick start guide (printed)
ControlNet BNC termination cap (1 piece)
Anti-static protective bag
Note: Cables, power supplies, and programming software are not included. The package does not contain any calibration certificate or warranty card.
All orders are dispatched via FedEx, UPS, or DHL within 24–48 hours after order confirmation. Tracking numbers are provided via email. International shipping typically takes 3–7 business days, depending on the destination. We ensure secure packaging to prevent damage during transit.
1. Can the 1768-CNB support redundant media operation?
No, this module only supports non-redundant media via its BNC connector. For media redundancy, you may need an additional redundant module or a different product from the ControlNet family.
2. How many nodes can I connect using the 1768-CNB?
The 1768-CNB supports up to 99 nodes on a single ControlNet network. This includes all controllers, I/O adapters, and HMI devices.
3. Is the 1768-CNB compatible with older ControlNet devices?
Yes, the 1768-CNB follows standard ControlNet specifications. It works with legacy devices as long as they comply with the same 5 Mbps baud rate and network protocols.
4. What should I do if the module status LED shows a solid red light?
A solid red LED indicates a major fault. First, check that the backplane connection is secure. Then, verify that the node address is unique and within the valid range (1–99). If the problem persists, consult the user manual for diagnostic codes.
5. Does this module require external cooling or special ventilation?
Under normal conditions, forced-air cooling is not mandatory. However, if you install multiple modules in a tightly packed enclosure, ensure adequate airflow to keep the ambient temperature below 60 °C.
| Brand Name | |
| Model No. | 1768-CNB |
| Product Type | Communication Interface |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
