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Ethernet interconnection between two embedded PC's inside one box

Hi,

I have a question about interconnecting two embedded PC's by Ethernet. Our situation:

- PC A has the LXT9785 Ethernet PHY of Intel, internal termination, with 1:1 transformer and 1nF/2kV capacitor at the TX and RX center taps at the secundairy side.

- PC B has the 82562ET Ethernet PHY of Intel, termination near PHY, without 1:1 transformer. The specification of this ethernet PHY describes the use of a 1:1 transformer with a 75ohm in series with a

1.5nF/2kV capacitor at each center tap at the secondairy side.

Question: has someone experience with interconnecting Ethernet ports of two embedded PC's without using a transformer at one of the PC's, in our case PC B? What are the consequences, limitations or general issues? The distance between these two PC platforms is apporx. 15 centimeter.

All suggestions are welcome.

Kind regards, Bert

Reply to
Bert
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If both embedded PCs have the same potential (GND to GND = 0 Volt) and the distance is "short" then: *) You can drop both PHY and wire MAC to MAC.

If potentials differ or the distance is too long. Then you can: *) Remove one magnetics transformer.

This ofcourse requires that all persons handling the equipment are aware of this issues when handling units or expanding them. Ie a motor drive on one of them may make the first solution unsuitable. The second solution requires that the network wire isn't reconnected to any other unit that is also unisolated.

Reply to
sky465nm

Bert,

Can these two PCs connect to each other by a hub or switch ??

If so then a cross over cable will work just fine.

donald

Reply to
donald

^^^^^ Sounds a bit cheesy to me.

Reply to
JosephKK

Much of Ethernet's cost is in the interface to that unshielded twisted long wire.. You can omit transformers and such, but... why Ethernet at all? Multiprocessor communication is usually through shared (two-port) RAM, isn't it? Or even a pair of FIFO RAMs?

I'd either use a standard processor board with the full Ethernet hardware, and treat the ports as useful for breaking out signals for maintenance, OR go with a full-custom shared memory.

Reply to
whit3rd

I understand that there arte better solutions for communication between two PC's, but in this system we have not the opportunity to chose another interface. Ethernet is the only available interface. Thank you all for your suggestions !!!

Reply to
Bert

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