24 V dc power with Ethernet specification
Like a round peg in a square hole, end-users can face incompatibility when designing and deploying 24 V auxiliary power on the factory floor. In response, ODVA is creating a "Power with Ethernet" specification for ODVA's networks based on Common Industrial Protocol (CIP). The 24 V dc auxiliary power specification is expected this month. Link to separate Power over Ethernet Plus information.
Like a round peg in a square hole, end-users can face incompatibility when designing and deploying 24 V auxiliary power on the factory floor. In response, ODVA is creating a "Power with Ethernet" specification for ODVA's networks based on Common Industrial Protocol (CIP). The 24 V dc auxiliary power specification is expected this month, according to reports made at the 2009 CIP Networks Conference & 13th Annual Meeting, Feb. 24–26.
The 24 V dc output power from an EtherNet/IP compatible device would run in a separate cable from the cable used for Ethernet data (as opposed to the IEEE Power over Ethernet, PoE, specification, which goes through the same wires), says Bob Lounsbury, chair for the ODVA EtherNet/IP Physical Layer Special Interest Group (SIG).
Total current in the system, as seen by power supply PS1, is the sum of the currents at each device (load): ltotal = IL1 + IL2 + IL3.
The power (actually 18–24 V dc depending on distance from the source) would operate e-stops, I/O sources and devices, actuators, and controllers—all of which may need more power than PoE or PoE-Plus wire can deliver, explains Lounsbury, who is also a principal engineer at Rockwell Automation. Work on the specification has involved several ODVA CIP groups, including the DeviceNet Physical Layer SIG. That group began considering 24 V dc power for CIP devices five years ago, covering topology, cable, and connectors. (The system is designed to provide no less than 18 V dc.)
Among details expected in the specification are support for:
Star, linear, and daisy chain topologies;
4-pin mini and micro connectors; and
5-pin IP67 connectors (compatible with Profibus).
Safety also is being considered, Lounsbury says, by ensuring male pins wouldn't be exposed, and trying to make sure damage wouldn't occur if cables were accidently plugged in where they shouldn't be.
Also read: Power over Ethernet Plus for factory automation . Have you looked at PoE and Power with Ethernet? Which is better for what? Share your views and experiences using the posting TalkBack tool below.
For other recent ODVA coverage, see:
Mark T. Hoske is Control Engineering editor in chief. Reach him at MHoske@cfemedia.com .
- Events & Awards
- Magazine Archives
- Oil & Gas Engineering
- Salary Survey
- Digital Reports
Annual Salary Survey
Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.
There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.
But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.
Read more: 2015 Salary Survey