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Daisy chain breaks up if I depower one of my evaluation boards

Thread Summary

The user encountered issues with the data-pass-through feature on EVAL-ADIN2111D1Z boards when daisy-chaining them with a Wago Media Converter 852-1705. The link between modules #1 and #3 failed when module #2 was depowered, despite the bypass relay connecting the signal paths. The solution is to remove resistors R31, R62, R63, and R64 to prevent the inductors and capacitor from disturbing the 10BASE-T1L signal, allowing unpowered boards to daisy-chain without issues.
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Category: Hardware
Product Number: ADIN2111

Hey,

I ran into a problem with the daisy-chain boards EVAL-ADIN2111D1Z. I bought four of theses boards and set it up in a chain with a Wago Media Converter 852-1705, which is based on a ADIN1100 as far as I know.
I have connected 24V power to all modules from the same source. Then I have configured individual IP addresses for each board via USB. Access of the firmware web page was then possible for all modules and I could see the expected firmware pages with the connection parameter and statistics. So far so good!

my_network - Wago-MC - #1 - #2 - #3 - #4

Now I started to try the data-pass-through feature, but I am struggling to bring it to work.
I disconnect the power source of device #2 and am expecting that I still be able to see the devices #3 and #, because of the internal data-bypass relais that kicks in.
So basically the module#1 should establish a link to module #3 across the relay of the depowered #2.
This is unfortunately not the case. The link on module #1 and module #3 are both down, and resets or power cycles do not change the state.

I measured the bypass function with a multimeter and it connects the P1-D+ with P2-D+ and also the D- of both ports correctly, but the expected link between #1 and #3 is not established.

I can see that the LED on device #1 on the port (P1) going to #2 (P2) is not flashing anymore, and the firmware web page of #1 is also reporting "link down" for P1.

If I plug in the power for #2 back, the link comes up immediately and is working fine, so I can see all 4 devices on my_network.
I have used short twisted pair wires between the boards, length 0.30cm (12inch).
I played with connecting the earth and common grounds between the boards with no success.

Has any one experience with the daisy-chain with the bypass relay on the D1Z modules? Is it working for you?
Do you see somehing I have not understand correctly or have any idea what possible reasons this may have?
What would be the next best step to understand the problem and fix it?

Attached see the foto of the faulty state and  some pictures of the web UI, the first three show the first three modules all connected and powered on. The last picture shows Modul #1 only (10.0.0.35) with the link P1 down, although module #2 on P1 is relay-bridged and module #3 is powered on.



This is #1 after disconnection the power from module #2 showing the link P1 to module #2 down:




  • Hi  

    Thank you for reaching out to us.

    The EVAL-ADIN2111D1Z uses two power inductors and a capacitor on the signal path to couple and forward power. These affect the performance of the 10BASE-T1L link if the power is lost. 

    If the purpose of the board is only to daisy-chain data and not power, remove the resistors R31, R62, R63 and R64. This prevents the inductors along with the capacitor from disturbing the signal. In that case, the signal passes only through the relay. This allows to daisy-chain multiple unpowered boards without problems. 

    If the relay is OK and connects the signal paths, the link will come up.

    Kind Regards,

    Shazia

  • Dear Shazia,
    thnaks for your reply. This does mean thath the power forwarding with the inductors and the data forwarding with the relay can not be used simultaniously. I will try out if the removal of the 4 resistors will allow the data forwarding if I supply the devices externally and one is cut of from power.
    Is it possible at all (maybe with different inductors) to forward the power without compromising the data signal?

  • Hi  

    Yes, it is possible to forward power without compromising the 10BASE-T1L data signal, this may require increasing the value of the inductors. This still introduces limits for number of nodes used in the daisy-chain. 

    The EVAL-ADIN2111D1Z board was tailored to be used for daisy chaining both power and data together, or bypass the data path in case of local power used, but in scenarios where power forwarding isn’t needed, removing R31, R62, R63, and R64 ensures the signal path remains clean through the relay alone. This allows to daisy-chain multiple unpowered boards without significant limitations. 

    Regards,

    Shazia