Feimu Technology Company has recently introduced an essential module to its overseas industrial automation partners. As everyone who uses Rockwell's PLCs knows, if there is a need to establish a fast and highly reliable connection between different racks or between the controller and remote IO, the ControlNet bus is a good choice. And this module is the core for achieving this. As a professional spare parts supplier, we recommend this durable and extremely stable bridge to you, in order to ensure that all your devices work obediently in a single bus and the data transmission is smooth and reliable.
The performance of this Allen Bradley 1756-CNB is quite robust. It has a high data throughput and can transmit both control signals and data with extremely high time requirements on the same bus. Its communication speed is adjustable and can adapt to 5M, which is ultra-high-speed transmission, or slower speeds, with high flexibility. What's most reassuring is its certainty. In the ControlNet network, it guarantees that data will definitely be transmitted within the specified time and will never be late like ordinary Ethernet due to congestion, which is extremely important for safety control.
|
Product Series |
Allen-Bradley 1756-CNB |
|
Communication Type |
ControlNet Communication Module |
|
Number of Ports |
2 x BNC Ports (Supports Redundancy) |
|
Communication Rate |
5 Mbps |
|
Nodes Connected |
Up to 99 Nodes |
|
Backplane Current |
1.2 A @ 5V DC |
|
Operating Temperature |
0°C to 60°C (32°F to 140°F) |
Many of the disassembly parts sold have the red address switch either loose, stuck, or even lacking a dust cover. Here, before shipment, we will use professional cleaning agents to wipe the outer shell clean, ensuring that the labels are clearly visible. Moreover, we will carefully inspect the rotary switch to ensure that each position can be accurately operated, making it particularly convenient for you to set the node address on-site.
ControlNet is a deterministic network protocol. Unlike standard Ethernet, ControlNet guarantees data delivery within a fixed time. This is essential for safety-critical and motion control applications.
Key features of ControlNet:
Why ControlNet is still used:
Proper network planning is critical for reliable ControlNet operation. Use these guidelines to plan your network.
| Parameter | Limit | Consequence of Exceeding |
|---|---|---|
| Nodes per network | 99 maximum | Network update time increases. Nodes may timeout. |
| Cable length per segment | 1000 meters (RG-6) | Signal attenuation. Communication errors. |
| Repeaters per network | 5 maximum | Signal delay. Network instability. |
| Network Update Time (NUT) | 2ms to 100ms | Short NUT reduces available data bandwidth. Long NUT slows control response. |
| Terminators | 2 required (both ends) | Signal reflections. Communication failure. |
Recommended cable types:
Field issue example: A customer used RG-58 cable on a ControlNet network. The system had intermittent communication errors. Modules would drop off the network randomly. Cause: Cable impedance mismatch. Fix: Replaced all cables with RG-6. Terminated both ends. Communication stabilized immediately.
The Allen Bradley 1756-CNB has different firmware versions. Older versions may not work with newer RSLogix 5000 software. Check firmware compatibility before installation.
| Firmware Version | Compatible RSLogix 5000 Version | Notes |
|---|---|---|
| Version 1.x | RSLogix 5000 v10 or earlier | Very old. May not work with newer versions. |
| Version 2.x | RSLogix 5000 v11 to v15 | Limited compatibility. |
| Version 3.x | RSLogix 5000 v16 to v19 | Widely used. Good compatibility. |
| Version 4.x | RSLogix 5000 v20 and above | Recommended. Best compatibility with new software. |
What Feimu does before shipping:
Firmware upgrade note: The 1756-CNB firmware cannot be upgraded in the field. It is burned into the module at the factory. The only way to get a newer version is to purchase a module with the newer firmware. Feimu can help identify the correct version for your system.
The 1756-CNB has two rotary switches on the front panel. These set the node address. Correct node address setting is essential for network operation.
Node address setting:
Common mistakes:
Recommended practice:
The 1756-CNB has several LEDs on the front panel. These provide immediate status information without a programming terminal.
| LED | Status | Meaning | Action |
|---|---|---|---|
| PWR | Green | Module powered and operating normally. | No action needed. |
| PWR | Off | No power to module. | Check chassis power. Check that module is inserted. |
| OK | Green | Module running. No faults. | No action needed. |
| OK | Red | Module fault. Hardware failure or configuration error. | Reinsert the module. If red remains, replace module. |
| OK | Flashing | Module is in configuration mode. | Download configuration from RSLogix 5000. |
| CH A | Green | Channel A active. Network communication present. | No action needed. |
| CH A | Yellow | Channel A communication warning. | Check cable. Check terminator. Check for noise. |
| CH A | Red | Channel A communication fault. | Check cable connection. Check termination. Replace cable if damaged. |
| CH B | Same as CH A | Channel B status. | Same actions as CH A. |
Allen Bradley 1756-CNB modules are commonly counterfeited. Use these checks to verify authenticity.
If the module shows red OK LED after proper configuration, suspect a counterfeit. Contact Feimu Technology with photos for verification.
Feimu Technology operates from Jiangmen City, Guangdong Province, China. The company was founded in 2005 and has supplied automation components to customers in over 30 countries.
Contact information:
Email: sales@feimutech.com
WhatsApp: +86 13358323579
Website: www.feimuplc.com
Response time: Within 24 hours. Technical questions typically answered within 12 hours. Include module serial number and firmware version when contacting.
Address
No. 26, Yuhu Street, Encheng Subdistrict, Enping City, Jiangmen City, Guangdong Province, China
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