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Allen-Bradley 1756-CN2 Communication Module
Manufacturer:Allen Bradley
Product Number:1756-CN2
Product Type:Communication Module
Origin:USA
Dimensions:~145 mm × ~35 mm × ~120 mm
Weight:0.293 kg
Views:133
Payment Methods:T/T, PayPal, Western Union
Condition:New & In Stock
Warranty:1 Year
Lead Time:1-3 Working Days
Certificate:COO
Courier partners:DHL, UPS, TNT, FedEx and EMS.
Business hours:7*24
Product Description
The Allen-Bradley 1756-CN2 is a communication bridge module designed for the ControlLogix® system. It serves as a dual-channel interface for the ControlNet network, enabling high-speed deterministic communication between controllers, I/O modules and remote devices. With its capacity for redundant channel operation, the 1756-CN2 is suitable for demanding automation systems where reliability, network performance and system integrity matter.
In a ControlLogix rack, the 1756-CN2 integrates seamlessly with other 1756-series modules and provides the backbone for ControlNet segments, making it a key element in architectures that require real-time deterministic control at the network layer.
Product Parameters
| Parameter | Specification | Notes / Comments |
|---|---|---|
| Number of channels | 2 (ControlNet A and B) | Enables dual-channel/control redundancy. |
| Maximum nodes supported | Up to 99 nodes | On a ControlNet segment with this bridge. |
| Maximum connections | 128 connections | Logix communication connections limit. |
| Transmission rate (ControlNet) | 5,000 kbps (5 Mbps) | Standard ControlNet network speed. |
| Power dissipation | ~6.7 W | Typical for module under load. |
| Current draw @ 5.1 V DC | ~1,300 mA | Operating current draw. |
| Current draw @ 24 V DC | ~3 mA | Auxiliary current draw. |
| Operating ambient | 0 °C to +60 °C | Standard industrial ambient. |
| Storage temperature | –40 °C to +85 °C | Non-operating condition. |
| Relative humidity | 5 % to 95 % non-condensing | Environmental tolerance. |
| Shock rating | 30 g | Operating mechanical shock resilience. |
| Vibration rating | 2 g @ 10-500 Hz | Operating vibration resilience. |
| Dimensions (H × W × D) | ~145 mm × ~35 mm × ~120 mm | Approximate module size. |
| Weight | ~0.293 kg (≈0.65 lb) | Approximate weight of the module. |
Application Scenarios
The 1756-CN2 is typically employed in automation systems requiring real-time, deterministic communication via ControlNet. Typical scenarios include:
-
Redundant ControlNet networks in critical process plants (chemicals, petro-chemical, oil & gas) where uptime is essential.
-
Large machine automation installations where multiple controllers, I/O racks and drives communicate over ControlNet segments.
-
Integration of legacy ControlNet installations into newer ControlLogix architecture, using the 1756-CN2 as bridge module.
-
Distributed I/O systems where remote racks need to be interconnected reliably with minimal latency and robust network design.
-
Control systems requiring dual-channel (A/B) ControlNet redundancy for fault tolerance and high availability.
Advantages (Key Strengths)
-
Dual Channel Support & Redundancy: The 1756-CN2 supports two independent ControlNet channels (A and B), enabling redundant network paths and improved system reliability.
-
High Node & Connection Capacity: With support up to ~99 nodes and up to ~128 Logix connections, it scales to large systems with many devices and I/O points.
-
Seamless Integration in ControlLogix: As a part of the 1756 series, it plugs into the standard backplane of ControlLogix chassis, simplifying installation and system design.
-
Deterministic Network Performance: Utilizes ControlNet protocol with fixed timing and priority scheduling, beneficial in time-critical control loops.
-
Robust Industrial Design: Rated for industrial ambient temperatures, vibration and shock; suitable for panel installation in real-world environments.
-
Simplified System Architecture: By using one communication bridge module for dual channels, wiring and system layout can be optimized.
FAQs(10)
-
Q: Can the 1756-CN2 be used for non-redundant ControlNet segments?
A: Yes — although it supports dual channels, one channel may be used, but full redundancy benefits require both channels populated.
-
Q: What is the maximum number of Logix communication connections this module supports?
A: The technical specification states up to 128 Logix connections.
-
Q: Does the module support ControlNet repeaters or hubs upstream?
A: Yes — standard ControlNet network design rules apply (repeaters, taps, segment length) and the 1756-CN2 functions as the controller-side interface.
-
Q: What is the slot width of the module in a 1756 rack?
A: The module occupies one slot width in a standard ControlLogix chassis.
-
Q: Can I use both channels (A and B) concurrently for separate networks?
A: Yes — you may use separate ControlNet channels for A and B for segregated traffic or redundancy as system design dictates.
-
Q: Is firmware required for compatibility between the 1756-CN2 and controllers?
A: Yes — ensure that the firmware revision of the 1756-CN2 is compatible with controller firmware and Logix Designer version.
-
Q: What is the maximum number of nodes supported per channel on ControlNet?
A: The module indicates support up to 99 nodes across the channel, but actual node count depends on the network design and load.
-
Q: What is the approximate power dissipation of the module?
A: Approximately 6.7 W under typical load conditions.
-
Q: Does the 1756-CN2 support peer-to-peer messaging over ControlNet?
A: Yes — it supports messaging via Logix connections and ControlNet scheduled data; design should align with network architecture.
-
Q: Are there conformal-coated or extended temperature variants of this module?
A: Yes — variants such as 1756-CN2RXT and others exist for extended or rugged environments.
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Allen-Bradley 1756-CN2 Communication Module
Manufacturer:Allen Bradley
Product Number:1756-CN2
Product Type:Communication Module
Origin:USA
Dimensions:~145 mm × ~35 mm × ~120 mm
Weight:0.293 kg
Views:133
Payment Methods:T/T, PayPal, Western Union
Condition:New & In Stock
Warranty:1 Year
Lead Time:1-3 Working Days
Certificate:COO
Courier partners:DHL, UPS, TNT, FedEx and EMS.
Business hours:7*24
Product Description
The Allen-Bradley 1756-CN2 is a communication bridge module designed for the ControlLogix® system. It serves as a dual-channel interface for the ControlNet network, enabling high-speed deterministic communication between controllers, I/O modules and remote devices. With its capacity for redundant channel operation, the 1756-CN2 is suitable for demanding automation systems where reliability, network performance and system integrity matter.
In a ControlLogix rack, the 1756-CN2 integrates seamlessly with other 1756-series modules and provides the backbone for ControlNet segments, making it a key element in architectures that require real-time deterministic control at the network layer.
Product Parameters
| Parameter | Specification | Notes / Comments |
|---|---|---|
| Number of channels | 2 (ControlNet A and B) | Enables dual-channel/control redundancy. |
| Maximum nodes supported | Up to 99 nodes | On a ControlNet segment with this bridge. |
| Maximum connections | 128 connections | Logix communication connections limit. |
| Transmission rate (ControlNet) | 5,000 kbps (5 Mbps) | Standard ControlNet network speed. |
| Power dissipation | ~6.7 W | Typical for module under load. |
| Current draw @ 5.1 V DC | ~1,300 mA | Operating current draw. |
| Current draw @ 24 V DC | ~3 mA | Auxiliary current draw. |
| Operating ambient | 0 °C to +60 °C | Standard industrial ambient. |
| Storage temperature | –40 °C to +85 °C | Non-operating condition. |
| Relative humidity | 5 % to 95 % non-condensing | Environmental tolerance. |
| Shock rating | 30 g | Operating mechanical shock resilience. |
| Vibration rating | 2 g @ 10-500 Hz | Operating vibration resilience. |
| Dimensions (H × W × D) | ~145 mm × ~35 mm × ~120 mm | Approximate module size. |
| Weight | ~0.293 kg (≈0.65 lb) | Approximate weight of the module. |
Application Scenarios
The 1756-CN2 is typically employed in automation systems requiring real-time, deterministic communication via ControlNet. Typical scenarios include:
-
Redundant ControlNet networks in critical process plants (chemicals, petro-chemical, oil & gas) where uptime is essential.
-
Large machine automation installations where multiple controllers, I/O racks and drives communicate over ControlNet segments.
-
Integration of legacy ControlNet installations into newer ControlLogix architecture, using the 1756-CN2 as bridge module.
-
Distributed I/O systems where remote racks need to be interconnected reliably with minimal latency and robust network design.
-
Control systems requiring dual-channel (A/B) ControlNet redundancy for fault tolerance and high availability.
Advantages (Key Strengths)
-
Dual Channel Support & Redundancy: The 1756-CN2 supports two independent ControlNet channels (A and B), enabling redundant network paths and improved system reliability.
-
High Node & Connection Capacity: With support up to ~99 nodes and up to ~128 Logix connections, it scales to large systems with many devices and I/O points.
-
Seamless Integration in ControlLogix: As a part of the 1756 series, it plugs into the standard backplane of ControlLogix chassis, simplifying installation and system design.
-
Deterministic Network Performance: Utilizes ControlNet protocol with fixed timing and priority scheduling, beneficial in time-critical control loops.
-
Robust Industrial Design: Rated for industrial ambient temperatures, vibration and shock; suitable for panel installation in real-world environments.
-
Simplified System Architecture: By using one communication bridge module for dual channels, wiring and system layout can be optimized.
FAQs(10)
-
Q: Can the 1756-CN2 be used for non-redundant ControlNet segments?
A: Yes — although it supports dual channels, one channel may be used, but full redundancy benefits require both channels populated.
-
Q: What is the maximum number of Logix communication connections this module supports?
A: The technical specification states up to 128 Logix connections.
-
Q: Does the module support ControlNet repeaters or hubs upstream?
A: Yes — standard ControlNet network design rules apply (repeaters, taps, segment length) and the 1756-CN2 functions as the controller-side interface.
-
Q: What is the slot width of the module in a 1756 rack?
A: The module occupies one slot width in a standard ControlLogix chassis.
-
Q: Can I use both channels (A and B) concurrently for separate networks?
A: Yes — you may use separate ControlNet channels for A and B for segregated traffic or redundancy as system design dictates.
-
Q: Is firmware required for compatibility between the 1756-CN2 and controllers?
A: Yes — ensure that the firmware revision of the 1756-CN2 is compatible with controller firmware and Logix Designer version.
-
Q: What is the maximum number of nodes supported per channel on ControlNet?
A: The module indicates support up to 99 nodes across the channel, but actual node count depends on the network design and load.
-
Q: What is the approximate power dissipation of the module?
A: Approximately 6.7 W under typical load conditions.
-
Q: Does the 1756-CN2 support peer-to-peer messaging over ControlNet?
A: Yes — it supports messaging via Logix connections and ControlNet scheduled data; design should align with network architecture.
-
Q: Are there conformal-coated or extended temperature variants of this module?
A: Yes — variants such as 1756-CN2RXT and others exist for extended or rugged environments.
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