ControlNet Technology Overview

ControlNet provides many advantages for manufacturing automation applications:

  • Bandwidth for I/O, real-time interlocking, peer-to-peer messaging and programming — all on the same link
  • Deterministic, repeatable performance for both discrete and process applications
  • Multiple controllers controlling I/O on the same link
  • Multicast of both inputs and peer-to-peer data
  • Media redundancy and intrinsically safe options
  • Simple installation requiring no special tools to install or tune the network
  • Network access from any node
  • Flexibility in topology options (bus, tree, star) and media types (coax, fiber, other)
Producer/Consumer Communication

ControlNet is based on an innovative solution in open network technology: the Producer/Consumer model. Unlike its predecessors, the Producer/Consumer model permits all nodes on the network to simultaneously access the same data from a single source. Ultimately, this model provides:

  • Greater system performance for higher productivity.
  • Increased efficiency because data needs to be produced only once, regardless of the number of consumers.
  • Precise synchronization because data arrives at each node at the same time.

ControlNet's Producer/Consumer model is more efficient than the older network communication models that used Source/Destination or point-to-point communication and required greater bandwidth to send the same data multiple times to different destinations. These models made synchronization between nodes very difficult because data arrived at a different time to each node. With Producer/Consumer, the data has a unique identifier, so multiple nodes can consume the same data at the same time from a single producer. As a result, bandwidth use is more efficient and nodes can be synchronized. 

Physical Layer Flexibility

ControlNet's cost-effective performance is further enhanced by flexible installation options, widely available RG-6 quad shield cable, and simple taps with no minimum spacing requirements.ControlNet supports any media topology including Bus, Tree, Star and combinations using repeaters. Four versions of Network Taps provide flexible mounting options: "Y", "T", straight or right ended.

Technical Specifications

Type of Bus

  • Control
  • I/O data, Programming Data on Same Wire

Bus Topologies

  • Linear Trunk
  • Tree
  • Star
  • Mix of Any of Above
Bus Speed:  5.0 megabit/sec (maximum)

Length, Single Segment

  • 1,000 m (coax) @ 5 Mb/s (1,000 m with two nodes, 250 m with 48 nodes)
  • 3,000 m (fiber) @ 5 Mb/s

Number of Repeaters

  • 5 (maximum) in Series
  • 6 Segments (5 repeaters) in Series
  • 48 Segments in Parallel

Maximum Length with Repeaters

  • 5,000 m (coax) @ 5 Mb/s
  • 30+ km (fiber)

Types of Repeaters

  • High Voltage AC & DC
  • Low Voltage DC
Device Power:  Devices Powered Externally

Connectors (Standard Coax BNC)

  • Barrel (plug-to-plug)
  • Bullet (jack-to-jack)
  • Extender (plug-to-jack)
  • Isolated Bulkhead (jack-to-jack)
  • Right Angle (plug-to-jack)

Communication Model:  Producer/Consumer

Number of Nodes

  • 99 Maximum Addressable Nodes
  • 48 Taps (nodes) without a Repeater

Size of Data Packet:  Variable, 0-510 bytes

Number of I/O Data Points:  No Limit

Network Update Time (Scan Time):  2-100 msec (user selectable)

Communication Modes (Bus-Addressing)

  • Master/Slave
  • Mulit-Master
  • Peer-to-Peer

I/O Data Triggers

  • Polling
  • Cyclic
  • Change-of-State
Cyclic Redundancy Check:  Modified CCITT Using 16-bit, Polynomial

Application Layer

  • Object-Oriented: Class/Instance/Attribute
  • Device Object Model using Device Profiles

Physical Media

  • Coax - R6/U
  • Fiber

Network and System Features

  • Remove/Insert Devices Under Power
  • Deterministic, Repeatable
  • Intrinsic Safety Option
  • Duplicate Node ID Detection
  • Message Fragmentation (block transfers)

 

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