Durante todo el año recibimos muchos mail, pidiéndonos información para realizar trabajos sobre autómatas. Así que ahora es el momento para recordaros que necesitamos de vuestra colaboración enviándonos los que ya habéis presentado.

Why ControlNet?

From proprietary to public standard, the proliferation of industrial networks offers users various benefits, but unfortunately from different networks. Couple this with the flattening of architectures and demands for higher performance, and you can see there was a need for an automation and control network that combined the benefits of several networks onto one link for increased system performance. Also needed was a control network to reliably predict when data will be delivered and ensure transmission times are constant and unaffected by devices connecting to, or leaving, the network.

These realities drove the development of ControlNet ... a real-time, control-layer network providing high-speed transport of both time-critical I/O data and messaging data, including upload/download of programming and configuration data and peer-to-peer messaging, on a single physical link. ControlNet's high-speed (5 Mbits/sec) and configurable data transmission capabilities significantly enhance I/O performance and peer-to-peer communications.

Taking full advantage of the Producer/Consumer model, ControlNet allows multiple controllers to control I/O on the same wire. This provides significant advantage over other networks, which allow only one master controller on the wire. ControlNet also allows multicast of both inputs and peer-to-peer data, thus reducing traffic on the wire and increasing system performance.

ControlNet is highly deterministic and repeatable -- critical requirements for ensuring dependable, synchronized and coordinated real-time performance. Determinism is the ability to reliably predict when data will be delivered, and 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.

ControlNet provides

	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
	All data maybe multicast, including inputs, outputs, and peer-to-peer
	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 (bus, tree, star) and media types (coax, fiber, other)

How it works

Network access is controlled by a time-slice algorithm called Concurrent Time Domain Multiple Access (CTDMA), which regulates a node's opportunity to transmit in each network interval. You select the length of the network interval by selecting a network update time (NUT). For example, 2ms, 20ms, 50ms, etc. The fastest NUT you can specify is 2 ms.

Information that is time-critical is sent during the scheduled portion of the network interval. Information that can be delivered without time constraints (such as configuration data) is sent during the unscheduled part of the network interval. Time-critical control data is delivered every NUT in a deterministic, repeatable fashion. Non-time-critical data is delivered as unscheduled time permits.

Where does ControlNet fit?

Plant-floor architectures are flattening into three layers:

	Information layer for plant-wide data collection and program maintenance Example: Ethernet
	Automation and Control Layer for real-time I/O control, interlocking, and messaging Example: ControlNet
	Device Layer for cost-effective integration of low-end devices Example: DeviceNet, Foundation Fieldbus

ControlNet meets the demands of real-time, high speed applications at the Automation and Control Layer for integration of complex control systems such as coordinated drive systems, weld control, motion control, vision systems, complex batch control systems, process control systems with large data requirements, and systems with multiple controllers and human-machine interfaces. ControlNet is ideal for systems with multiple PC-based Controllers, PLC-to-PLC and PLC-to-DCS communication.

ControlNet Architecture Capabilities

ControlNet allows multiple controllers on a single link to share inputs while controlling their own outputs. Controllers can also talk to each other in any possible combination with both scheduled interlocking data and unscheduled messaging data.

Producer/Consumer Communication

The Basis of ControlNet's Advanced Features

The capabilities of traditional networks cannot satisfy the ever-increasing demands for higher productivity and greater system performance, while providing for repeatable and predictable communication between devices. Higher baud rates and greater protocol efficiency, alone, are not enough to meet the challenge. A state-of-the-art approach is needed for the basic technology of how a network manages communications with connected devices (nodes).

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

The "New" Communication Model

Older network communication models use "Source/Destination" or point-to-point communication models. Source/Destination wastes bandwidth as like data must be sent multiple times when only the destination is different. Also, synchronization
between nodes is very difficult as data arrives at a different time to each node.

With Producer/Consumer, the data has a unique identifier. Using this model, multiple nodes can consume the same data at the same time from a single producer, resulting in more efficient use of bandwidth. Also, nodes can be easily synchronized.

Example: Communicate the current time-of-day to a room of twenty (20) people.

Source/Destination Model

One person ("source") tells each person ("destinations") in the room, one at a time, the current time-of-day (data).

INEFFICIENCIES

	Excess Data Transmission - some people may choose to listen; others may choose to ignore.
	Data Inaccuracies - Time will pass during multiple transmissions, compromising data accuracy.
	Determinism Fluctuations - The length of time to deliver data is dependent on the number of people in the room.

Producer/Consumer Model

One person ("Producer") tells ALL people ("Consumers") in the room AT THE SAME TIME the current time-of-day (data).

HIGHLY EFFICIENT

	Economy of Data Transmission - No wasted effort delivering data to those who do not care.
	Accurate Data - No adjustments to data needed since everyone received the data at the same time.
	Deterministic - Length of time to deliver data is independent of the number of people in the room.