ControlNet Overview And Description

CONTROLNET: The High Level, Mission Critical Fieldbus

Origin: Allen-Bradley, 1995

Based on RG6/U cabling (popular in cable TV applications) and Rockwell ASIC chip

Maximum Number of Nodes: 99

Connectors: Twin redundant BNC

Maximum Distance: 250 to 5000M (with repeaters)

Baudrate: 5 Mbit/Sec

Message Size: 0-510 bytes

Messaging Formats: Based on Producer/Consumer model; multi-master, peer to peer, fragmented, prioritized and deterministically scheduled repeatable messages; dual transmission paths for built-in redundancy.

Supporting Trade Organization: ControlNet International, http://www.controlnet.org/

Typical Applications: Mission critical, plant-wide networking between multiple PC’s, PLC’s and sub-networks (i.e. DeviceNet, Foundation Fieldbus H1, etc.) and process control, and situations requiring high-speed transport of both time-critical I/O and messaging data, including upload/download of programming and configuration data and peer-to-peer messaging.

Advantages: Deterministic, repeatable, efficient use of network bandwidth, provides redundancy at lower cost than most other available networks including Ethernet. Can be transmitted on any IP transport protocol via Ethernet, Firewire or USB.

Disadvantages: Limited multi-vendor support and expensive Rockwell ASICs.

ControlNet: The Big Picture

ControlNet was conceived as the ultimate high-level Fieldbus network, and was designed to meet several high-performance automation and process control criteria. Of primary importance is the ability of devices to communicate to each other with 100% determinism while achieving faster response than traditional master/slave poll/strobe networks. (Determinism means knowing absolute worst-case response times with 100$ certainty.) This is made possible by the Producer/Consumer communication model and the Scheduler, which rigorously prioritizes messages.

Multi-Master and Repeatability

ControlNet allows multiple masters to control the same I/O points. Repeatability ensures that transmit times are constant and unaffected by devices connecting to, or leaving, the network. These features are further enhanced with user selectable I/O and controller interlocking update times to match application requirements.

Large Quantities of Data and Complex Devices

ControlNet is specifically designed to accommodate the high-level information and control needs of literally dozens of sub-networks and controllers. In process control situations where hazardous materials are involved and absolute certainty with respect to control processes is required, the deterministic capabilities of ControlNet are extremely important.

Redundancy

The ControlNet architecture has redundant connectivity as an integral feature. Redundancy is rather difficult to achieve with other networks, but each ControlNet node has dual connections for this very purpose.

Synergetic provides a number of useful ControlNet connectivity solutions:

Master Technology: If you are planning to design a ControlNet master scanner, we can supply sourcecode written in ANSI C, which implements the ControlNet protocol with the Rockwell ASIC. Synergetic is a Rockwell Design Partner for the ControlNet Master sourcecode. The license permits you to make and sell an unlimited number of ControlNet devices for a one-time license fee. (See the license agreement for specific details.)

WORLD’s FIRST CONTROLNET CERTIFIED PRODUCT: Our PC Adapter Cards. We have PC/ISA and PC104 Adapters for ControlNet. They use the same configuration tools*, hardware and software interface as all of our other Fieldbus interfaces (DeviceNet, Profibus, Interbus, etc…).

*Check for availability of our SYCON configuration tool for ControlNet; these cards can also be configured with Allen-Bradley RSNetworX Software.

Embedded Slave Modules: The ANYBUS-S ControlNet module allows you to design instant ControlNet, DeviceNet, Profibus, Interbus, and other Fieldbus connectivity into your product in a matter of weeks. Now you don’t have to be a ControlNet expert to manufacture a ControlNet-compatible product!

A custom hardware design is required, and all Fieldbus components, including connectors, are on the Anybus board. After designed in, all Anybus cards in the same family can be interchanged as different Fieldbuses require.

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