PLC Programming
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Allen-Bradley Implementation

ControlNet for Allen-Bradley

Deterministic network protocol for real-time control applications. Part of CIP family (Allen-Bradley/Rockwell).

Type: FieldbusSpeed: 5 MbpsReleased: 1997Organization: ODVA
5 Mbps
Bandwidth
99
Max Nodes
1000m (coax), 3000m (fiber)
Max Distance
Yes
Real-Time

Protocol Overview

Deterministic network protocol for real-time control applications. Part of CIP family (Allen-Bradley/Rockwell).

When to Use ControlNet

Choose ControlNet for existing installations or when upgrading legacy systems. For new projects, EtherNet/IP is recommended.

Technical Specifications

Physical Layer

  • Physical Layer: Coax or fiber optic
  • Cable Type: RG-6 coax or fiber optic
  • Topology: Bus, Star, Tree
  • Power Over Cable: No

Data Layer

  • Data Link: CTDMA (Concurrent Time Domain Multiple Access)
  • Encoding: Manchester
  • Error Detection: CRC-32
  • Frame Size: 510 bytes

Performance

  • Scan Time: 2-100ms (configurable NUT)
  • Deterministic: Yes
  • Real-Time: Yes

Certification

  • Certification Required: Yes
  • License Cost: ODVA conformance testing
  • Version: Current

Advantages & Disadvantages

Advantages

  • ✓Highly deterministic
  • ✓Repeatable performance
  • ✓CIP family integration
  • ✓Scheduled and unscheduled traffic
  • ✓Good for motion control
  • ✓Redundant media option
  • ✓Hot-swappable taps

Disadvantages

  • ✗Expensive hardware
  • ✗Complex configuration
  • ✗Being superseded by EtherNet/IP
  • ✗Limited vendor support
  • ✗Specialized cable/taps required
  • ✗Lower speed than modern alternatives

Common Use Cases & Applications

High-speed assembly lines
Motion control systems
Critical manufacturing processes
Automotive paint shops
Legacy Rockwell installations

Industry Adoption

Adoption LevelLow (legacy)
Market Share<5% (legacy installations)
Geographic PresenceNorth America primarily
Primary Industries
AutomotiveDiscrete Manufacturing

Supported Message Types

Scheduled (time-critical)
Unscheduled (messaging)

Supported PLC Brands

Allen-BradleyRockwell

Quick Links

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