By default, the destination of the Output Data is the Indirect Data Map. Certification programs modeled after the programs for DeviceNet and ControlNet will ensure the consistency and quality of field devices. For example, a vendor of a Temperature Controller with multiple temperature loops may define assemblies for each of the temperature loops and an assembly with data from both temperature loops. Traditionally, Ethernet had only limited acceptance in Industrial Automation. Planning your Ethernet factory automation infrastructure is essential. A device vendor can also group Application Layer Objects into assembly objects.
Two of the most important challenges to the first time user include training and network configuration. The series of application objects for a particular device type is known as the device profile. Careful identification of all your control loops, choosing the correct routers, switches and paths and documenting your network properly are requisites for a communications network which meets your production goals and requires little ongoing maintenance. Instead of letting a user wait while a task is being performed, factory floor data communications needs are real-time or very close to real time. See the topic for details. These super objects contain attributes of one or more Application Layer Objects.
It defines the access, object behavior and extensions which allow widely disparate devices to be accessed using a common mechanism. A large number of profiles for many device types have been defined. See the topic for details on these settings. A Network object contains the physical connection data for the object. This data is strictly of the vendors choosing and is organized in whatever method makes sense to the device vendor.
The steps required for this are tool-specific. Note: David Letterman has his Top Ten. The object specifies attributes that describe the link, such as the node addresses and data rates. The identity object contains related identity data values called attributes. Supporting a device profile allows a user to easily understand and switch from a vendor of one device type to another vendor with that same device type.
Assembly objects form a convenient package for transporting data between devices. That instance identifies the connection as Explicit or Implicit, sets the packet rate on Implicit connections and holds other descriptive information on the connection. It allows users to share files, access printers, send email, search the Internet and perform all the other communications used in the office environment. An instance of the Connection object is generated for every connection. These objects include the Identity object, a Message Router object and a Network object.
Detractors of Ethernet applications on the factory floor often cite the lack of inherent determinism in Ethernet communications to keep it out of automation applications. Only the lack of a widely accepted, flexible application layer targeted to Industrial Automation has prevented its complete acceptance. For example, one temperature assembly may be configured to report every time it changes state while the second may be configured to report every one-second regardless of a change in state. These connection types are generally not used. A connection object is removed when the connection is closed.
These objects are included by the vendor as additional features of the device. These application layer objects are predefined for a large number of common device types. While true in the past, recent developments in intelligent switches have largely eliminated this argument. An Explicit Message Only device has no Assembly instances. This connection type is the least-frequently used. For example, a Motor object on a Drive System has attributes describing the frequency, current rating and motor size. The classification of all devices as objects decreases the training and startup required when new devices are brought online.
An Output Assembly instance organizes the data that is transferred from external devices. These switches create separate collision domains that offer the determinism required of almost all but the most demanding of automation applications. Until recently the expense, lack of intelligent switches and routers and the domination of large vendors with proprietary protocols prevented the wide acceptance of Ethernet on the factory floor. In these cases, additional connection configuration information usually must be entered into a generic device template. Messages sent over Explicit connections are directed to the target object by the Message Router object.