Ethercat back-to back MII connection, no PHY.

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User13948
Level 2
Level 2
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Hello,
I need to connect several XMC4800 on the same board and it would be great to only have two PHY chips, at the beginning and at the end of the Ethercat chain.
It seems it can be done, page 33: https://download.beckhoff.com/download/document/io/ethercat-development-products/ethercat_esc_datash...

I wired two relax boards in that way, but it doesn't work right now. I can provide details if needed.

- Is it supposed to work, or is there something basic that prevents it?
- Does the driver code needs to be changed? Following Beckhoff recommendation I set enable_enhanced_link_p1 : 0; in xmc_ecat.h and TX shift to 10 ns in DAVE ESC app. Is it enough?
- Any hint on how to debug this circuit?

Best regards.

Alberto
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4 Replies
jferreira
Employee
Employee
10 sign-ins 5 sign-ins First like received
Hi Alberto,

It should be possible. Are you using TwinCAT as EtherCAT master? Does it recognize the first slave in the chain?

Regards,
Jesus
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MichaelIFX
Employee
Employee
50 replies posted 25 replies posted 10 replies posted
We have setup a MAC2MAC connection with wild wiring between to XMC4800 Relax Kits and it worked out of the box with our basic example "ETHCAT_SSC_XMC48".
Please see attachment for details.

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User13948
Level 2
Level 2
First like received
Thank you for your effort, My tests were unsuccessful and the project proceeded with a standard two PHY setup.
Maybe in a next release we will try again.

Thanks again

Alberto
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User13948
Level 2
Level 2
First like received
Un unrelated question: what is the purpouse of the NC7SZ125M5X buffer on the PHY_RST of the Relax Board?

Best regards.

Alberto
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