POE hub connection failed

How to test

  • Laptop with no Wi-Fi connection
  • IP 192.168.0.xxx
  • Product with W5500 (x2)
  • POE switch hub
  1. Change the POE hub
  • Multicom : MD-6608 → Not working(We need to use this hub)
  • Other hub → Working
  1. Replace the POE hub port
  • Most of the time, it’s not working, but sometimes the connection is good
  • If the connection starts to fail by power cycling or changing the port, the connection will continue to fail
  1. One-on-one connection between POE Hub and Product
  • Not connected
  1. POE Hub to Product one-to-many
  • Good connection with product multiple connections
  • If the connection starts to fail by power cycling or changing the port, the connection will continue to fail

Good connection, bad connection, inconsistent conditions
If the connection is good, everything works well under any conditions, but if the conditions change and start not to work, it cannot continue
Similarly, in situations where the connection is not possible, it will continue to work well if the conditions are changed according to the test method above

Please find the why.

Thank you.

Several questions:

  1. what you man saying “connection failed”? No link LED on (at which side of cable)? W5500 can’t connect to some remote device? Or some remote device can’t connect to W5500? give as much detail on this as possible - how it works and how you identify it not working.
  2. You say " 3. One-on-one connection between POE Hub and Product" - I suspect it is about link LED? Because connecting hub and product (W5500) does not create any TCP or UDP user traffic.
  3. When there’s “no connection” did you try to power cycle (turn off and then on) the W5500 module and see the result?

Both the link LED connected to the W5500 and the PoE hub link LED are turned off.
I did more experiments and among PoE, the PoE called MD-6608 was not connected to some W5500. It’s not that the W5500 is not connected, but just a few W5500 are not.

It was misinformation. When I tested more, it was not a one-on-one problem, but a specific W5500 product could not be connected. And the LED doesn’t turn on either.

Yes, I repeatedly turned it off and on, but it didn’t connect.

Eventually, when I replaced the W5500S2E-Z1 module in the product, it was connected. But I want to find out why this phenomenon occurs. When I test it, it seems that when I connect MD-6608 (PoE) and W5500, I sometimes get a W5500 that is not connected.
However, if you use other PoE, all communicate normally. I don’t think this is a W5500 error or PoE issue.
If you know the cause, please let me know.

Thank you.

Seems requires more troubleshooting. Seeing how much current is being taken from the PoE in dynamic (draw he graph f the current consumption starting module plugging into the switch. What is going on the SPI and network lines. Trying to power from the external PSU instead of PoE.

I don’t know how to measure the current value consumed when using PoE. Instead, we measured the current value consumed when we put external power into our device and calculated the power. Three different devices were measured, and 5V external power was inserted, and the consumption current was 0.29A to 0.3A, respectively. When calculated, it was 1.41 W, so there was no difference between a defective device and a normal device.

Does it always connect when you put external power supply? In other words - does power source affect operation?

It always works. It does not affect operation.

I assume you meant that with external power supply it always works.

You use W5500S2E-Z1, and I see it does not have built-in PoE module. Evaluation board does not have it too. So you must be using your own PoE module, right? explanation or circuit diagram would help.

How do you drive nRST pin of the W5500S2E-Z1? Where is it connected, and how is it operated after you plug ethernet cable into the device?

I can’t explain how it works because it’s not a circuit diagram I made, but I have a circuit diagram, so I’ll attach it.

Let’s make small test. Take the W5500 module which does not connect (so that we can reproduce the issue with highest probability). Plug module into PoE, ensure it does not connect, LEDs are off. Then take tweezers and short circuit C18 - 1uF capacitor in the reset circuit - for a second. Be very careful not to short anything else nearby, and ensure you do it to C18 (and not to any power decoupling capacitors). Remove pincers and see if there will be any difference. Do it several times to see what happens every time. report your findings back.

When replacing the W5500S2E-Z1 module, there is a lot of damage to the module, making it difficult to test. Is there any other way?

How do you test without putting module into the working conditions? You take twisted pair cable, one side connect to switch, and another to module. You do not need to put it into the industrial chassis or perform any other actions damaging the module or infrastructure, just connect as required.