Ethernet Ip Sensors

The Plc Kid

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Feb 2009
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Macon, Georgia
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Why are there very few if any ethernet ip sensors like devicenet had.

Devicenet has intelligent sensors that give angle of limit switches,Photoelectric sensors that give lens dirty indication,etc.

Ethernet ip all you have is cameras an few encoders and pneumatic and on machine io blocks.

Ethernet should be able to have a cable with comms and power wires becase ethernet has POE. So the 24 vdc should not be a problem.I know the limitations of POE and that is not what i am proposing but seperate 24 dc wires in the cable like devicenet.

I have to use devicenet and ethernet on equipment. It would be nine to have all ethernet and 1 network.

I was just curios why this is not being done? are there limitations that i am not aware of?
 
Ethernet I/P is not marketed as a device level bus. Neither is ControlNet. They are intended for a higher level of communication. Neither of these was designed to do direct device communication. It doesn't necessarily mean they can't. It just isn't the marketing direction they are taking. There may be some valid technical reasons for this. But to a certain degree it is product differentiation.

Keith
 
Ethernet/IP really isn't a good idea for device-level parts, simply because of the communications resources it needs. Connecting to a rack, and getting an entire rack worth of data is one thing, but to have to use a communications buffer for single switches is quite another and very inefficient.

Running out of connections is really no fun... Trust me.
 
The software/hardware requirements for EtherNet/IP are quite high, it requires a full TCP/IP stack, and one that can handle a network segment with high bandwidth, so usually it requires a 32 bit microprocessor for the comms.

If your sensor / effector could normally be run by a 8 bit or 16 bit micro, that's going to be a large, multi-hundred dollar price adder to get EIP on their sensor / effector.
 
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I liked the the idea of Ethernet sensors but wondered if the next step would be wireless Lan sensors - they would have to get there power from somewhere though. Maybe the same idea as a big transformer at the base of the machine.

Might sound far fetched. I could of done with some as I had a carousel with only 8 signal slip rings. After Estop and a other important signals I had none left. Ended up putting a PLC in the middle of the carousel and wirelessly talking to the main controller.

I understand the cost but I am sure embedded 32bit processors are coming down in price and with this job it would of been cheaper to buy a few Wlan sensors than build a whole new control cabinet and a wireless link.

I know what you're thinking add some more slip rings. That's mechanical!!!
 
Well they have ethernet ip on the pneumatic valve blocks and have encoders with ethernet ip and the incresed cost is not that bad. I know photoelectrics and proxes are lower cost but i think it could be cost effective depending on the application.

Devicenet sensors are a much greater cost than standard sensors but they sell many of them.The increased data and options makes them worth the extra cost.
 
Devicenet sensors are a much greater cost than standard sensors but they sell many of them.The increased data and options makes them worth the extra cost.

If you would like to decrease the amount of wiring, especially in a larger machine, you may consider 'the best of two worlds' solution. See an Ethernet/IP coupler + 'slice' I/O modules from Wago or Beckhoff. This way you may be able to split your I/O into reasonable local groups; connect your sensors and actuators to the I/O modules locally and tie everything together with network cables.

Adding any networking functionality to a $20 prox sensor seems totally crazy to me.
 

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