Purchase now the 20-750-CNETC, a high-reliability coaxial ControlNet communication adapter designed specifically for the Allen-Bradley PowerFlex 750-Series of variable frequency drives. This module is the definitive solution for integrating modern motor control into established, deterministic ControlNet networks.
What Is the 20-750-CNETC?
The 20-750-CNETC is an internal communication option module that allows PowerFlex 753 and 755 drives to interface with a ControlNet network using coaxial media. ControlNet is a scheduled, deterministic network that excels in high-speed, repeatable data transfers, which is vital for synchronized industrial processes. The module plugs into the drive’s internal communication ports (typically Slot 4 through 8) and utilizes the Drive Peripheral Interface (DPI) protocol to exchange data with the drive’s main control board. It enables full access to the drive’s parameter set, allowing for remote start/stop commands, speed reference adjustments, and comprehensive diagnostic monitoring from a central controller like a PLC-5, SLC 500, or ControlLogix system.
Key Technical Specifications
- Protocol: ControlNet (Coaxial)
- Media: RG-6 Coaxial Cable with BNC connectors
- Communication Speed: 5 Mbps
- Module Compatibility: PowerFlex 753, 755, 755T, and 755TR
- Data Capacity: Supports scheduled and unscheduled messaging
- Isolation: 50V (continuous)
- Status Indicators: Integrated LEDs for Network, Module, and Link status
- Interface: DPI (Drive Peripheral Interface)
Deterministic Control Architecture
In a ControlNet architecture, the 20-750-CNETC ensures that critical control data arrives exactly when expected, regardless of other network traffic. This determinism is achieved through the Nut (Network Update Time) scheduling, which makes the 20-750-CNETC ideal for coordinated drive systems in metal rolling mills, paper processing, or printing presses. The module supports both «Producer/Consumer» and «Client/Server» models, allowing the drive to share status data with multiple devices simultaneously without increasing network overhead. It also facilitates the use of RSNetWorx for ControlNet to perform network scheduling and drive commissioning.
Maintenance Tips
To maintain peak performance of the 20-750-CNETC, always inspect the BNC connectors for oxidation or loose connections, as signal reflection in coaxial systems can cause intermittent network dropouts. Ensure that the ControlNet taps are correctly terminated with 75-ohm resistors at the physical ends of the trunk cable. If the «NET» LED flashes red, it typically indicates a MAC ID (Node Address) conflict or a scheduling error; use the drive’s Human Interface Module (HIM) to verify that the node address matches the configuration in your software.
Frequently Asked Questions
Q: Does the 20-750-CNETC support Device Level Ring (DLR)?
A: No, DLR is a feature of EtherNet/IP networks. ControlNet uses a different physical layer and topology. For ring redundancy, redundant coaxial media must be used if the module supports it.
Q: Can I change the node address while the drive is running?
A: While you can change the parameter, the 20-750-CNETC requires a power cycle or a module reset to apply the new MAC ID to the network.
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