Despite the marketing hype as to the value of Electronic Data Sheet (EDS) prior to 2012, there was no advantage to constructing EDS files with complete product data. Few, if any, tools were able to use these kinds of EDS files in the way they were intended.
Now, with V20 of RSLogix5000, this has all changed. This blog describes the changes and how device vendors can take advantage of these changes.
EDS File Overview
EDSs are simply ASCII files that describe how a device can be used on an EtherNet/IP network. It describes the objects, attributes and services available in the device.
At a minimum, an EDS file conveys the identity information required for a network tool to recognize the device. For EtherNet/IP scanners, the EDS file conveys information on the EtherNet/IP adapter’s I/O messages. It details the specifics of the input message produced by the EtherNet/IP adapter and the output message consumed by the adapter.
The amount of information stored in an EDS file varies from device to device. Some manufacturers store the minimum amount of information in the EDS file while other devices store all the details of every object and attribute in the device.
EDS files are sometimes shipped with a device in some media format like a CD or made available on the device manufacturer’s website. Some devices with extended data storage contain the EDS file internally within the device.
EDS File Structure
File Section – Administers the EDS file. Sometimes the URL keyword provides a link to a website where the latest version of the EDS can be found.
Device Section – Provides keying information that matches the EDS to a particular revision of a device. The first three attributes of the identity object (Object #1) are used by network tools to verify that this EDS file (vendor, model, etc.) plus the device revision matches the information found in the device. The network tool will not connect to a device unless all four identity object parameters match.
Some people mistakenly believe that the minor revision number is included in this match but that is not true.
ODVA recommends that the icon for the device be specified in the EDS so that users can have a graphical way of distinguishing devices.
Device Classification Section – Classifies the EDS for an EtherNet/IP network. It is required for all EtherNet/IP devices.
Connection Manager Section – Identifies the CIP connections that are available in the device. This section indicates to the EtherNet/IP scanner the triggers and transports available in the device. If a device supports multiple connections then every connection must be detailed in this section.
Only connections that are specified in this section can be used in an EDS-based configuration tool.
Assembly, Params and ParamClass section – These sections are filled in as needed. For values that are limited to a defined set of values, enumeration can be used to specify those values. Value ranges can be specified here also for configurable parameters.
Capacity Section – This section indicates the number of connections available in the device and the connection speeds
Port Section – This section describes the Ethernet port. It is only applicable to devices that perform CIP routing. It is unnecessary for devices containing a single CIP port.
EDS files also support definition of the Configuration block. The Configuration data block is simply a series of data words that are downloaded to device on power up or reset. These blocks provide one-time initialization of an EtherNet/IP device.
EDS File Checker
ODVA no longer provides the EDS File Checker to validate the configuration of EDS files. As far as I know, no other vendor is providing that tool.
ODVA is providing a tool called the EZ-EDS™ for EDS creation and maintenance. It reduces the time to create EDSs through intuitive user guidance and by providing support for all EDS constructs with extension capabilities for future sections and keywords. Using this utility, the EDS process is no longer a lengthy, iterative process, but a straightforward task that can be completed quickly and effectively.
Changes in V20 of RsLogix5000
After many years, V20 of Rockwell’s RsLogix5000 programming tool added support for EDS Files. Here’s a list of the changes:
Configuration Support – This version of RsLogix provides the capability for an end user to configure a device using the Enumeration, Ranges and other limitations imposed on a configuration parameter as specified in the EDS file.
Prior to this version, end users typically had to use a vendor tool, a web page, a built in display or some other mechanism to configure a device. Now configuration of all devices can be done from within one, identical tool.
Configuration Data Block Support – Configuration data blocks can now also be defined by RsLogix5000 if it is exposed as a meaningful data structure in the EDS File.
Module Discovery – You can now browse for devices on the network with supported EDS files and add them into the I/O scan list with a single button press. You no longer need to know the catalog number, slot number or network address to add a device to the I/O tree.
What’s Still Missing
I was disappointed to learn that, unlike the configuration data, the EtherNet/IP server’s input and output assemblies are still defined as Tags composed of a block of data even when the EDS has defined the structure in a meaningful way.