W5100 shield looses comunication with arduino due to interferences

Hi,

i am runing a variable frequency drive and some contactors from a mega. One time a motor gets supplied from mains directly and once from the VDF via two contactors. The contactors are switched by the mega.

always when the motor gets swiched on from the mains contactor, the w5100 looses communication (green and orange LED at RJ45 connector goes off) and IP address is not accessible for a two to three seconds) after this the connection recovers and the values i send via ethernet are back.

I have tried a short test by laying the ethernet cable apart from the rest of the cables. Then the phenomena occures not always. So i guess the ethernet shield is a bit sensitive to EMV.

My question is, can i restart the ethernet server via the mega somehow?

cheers

Why restart the server. Stop the failure. Do you have the contactors (relay?) controlled by a optocoupler and powered by a separate power source?

Hi,

yes the contactor -big relay ;) - is decoupled twice... first through an optocoupler which is switching a relay which i switches the contactor lately.

It looks more like the EMV interferes the communication.....

with restart i mean..... that in setup funktion you start the w5100 with "Ethernet.begin"..... is there a way to call occationally from loop funktion to begin again.....

cheers

always when the motor gets swiched on from the mains contactor, the w5100 looses communication (green and orange LED at RJ45 connector goes off) and IP address is not accessible for a two to three seconds) after this the connection recovers and the values i send via ethernet are back.

Sounds like both the Arduino and ethernet shield are restarting. Calling Ethernet.begin will not fix that.

When you say two contactors I am assuming these are three phase contactors, is this correct? If so, I am again making an assumption, as you don't detail your layout at all, that you have one contactor before the VSD and another elsewhere, is this correct ?

Most VSD units have a start/stop input which is at low voltage levels, typically 24Vdc, and this is where you should be controlling.

With this input, you can control the VSD by using a simply relay board connected to your Adruino, or by using an opto-islolator directly.

Then the phenomena occures not always. So i guess the ethernet shield is a bit sensitive to EMV.

It is not a phenomenon, and the EMV you refer to is called EMI, not EMV.

What ever you do, you do not place a contactor between the VSD amd the motor that you then control by Arduino while the VSD is operating, or you will strike troubles.

Many VSD units have Ethernet as a communications port, so it comes down to good electrical layout and containing potential EMI, by use of three phase line filters.

If you were to supply a wiring diagram, we would be better able to understand your system, together with VSD model number.


Paul