EtherNet/IP Physical Layer Implementation

If you are going to go about developing an EtherNet/IP device, what are the physical requirements that you must meet? Is it enough to just use off-the-shelf components? Can you just add some software and an RJ45 jack to your device and “TA DA”, you’re EtherNet/IP capable?

A key distinction that you have to make in your implementation is what level of reliability and ruggedness does your device and/or application require? You need to know how your device will be used, what kind of throughput is required, where it will be used…etc. The following is a quick summary of the ODVA standard but is not adequate for product development.

If your device simply exists in a clean, lab environment, or enclosed cabinet with no requirements for high speed operation (>100mb) a Commercial implementation will be adequate. In this type of implementation, you can use off-the-shelf components, support 10mbps and 100mbps and use a standard, non-sealed RJ45 or Fiber connector. Requirements for these kinds of devices can be found in the ANSI 802.3 and TIA 568 standard.

Devices meeting these commercial standards are often found in industrial environments. They usually perform well if the physical environment is not subject to temperature, vibration, shock, noise and other environmental extremes. The ODVA Physical Layer specification recognizes devices meeting commercial implementation standards as acceptable for use within the guidelines of the EtherNet/IP specification. However, products meeting these commercial standards are not eligible for the industrial conformance checkmark. These products are eligible only for the commercial conformance checkmark.

The ODVA specification goes to great pains to warn EtherNet/IP developers away from Commercial implementations. They prefer that developers follow the industrial standards and protect devices to the maximum against shock, vibration and other environmental extremes. They go to great pains in the specification to warn that commercial components and a commercial implementation can “degrade system performance” however the vast majority of EtherNet/IP device developers have followed the commercial implementation without problems.

Product developers, with requirements that exceed the 802.3 or 568 standards, should follow the Industrial implementation standard. Volume 2, Chapter 8 of the EtherNet/IP Physical Layer standard defines this standard. The standard defines the vibration, shock, humidity, temperature and EMI requirements for an Industrial Implementation.

These standards are all based on published standards. Vibration is based on IEC 60068-2-6. EMI is based on the IEC 61000-6 and IEC 61000-4. Temperature and Humidity standards are based on the IEC 60068-2 standard.

The ODVA Physical Layer specification also details the kinds of cabling that meet the Commercial and Industrial standards. The types of shielded and unshielded cables, the typical impedance, the wire color codes and the acceptable losses are all detailed by this standard. Sealed and unsealed RJ45 housings are both acceptable under the Industrial standard. Codings for the sealed housings are specified in the standard.

For more information on Physical Layer specifications you should contact the ODVA at its Ann Arbor, Michigan office. They can provide the most complete details on how to meet the Industrial standard.