@m26872 Thanks!
Wich library is better to use? UIPEthernet works well with W5100? I need a library that can handle client/server request.
Thanks very much!!!

HI! Thanks for the topic! I'm new on this forum and I'm using enc28j60 with UIPE Lib. I have a lot of hang-up in my sketch.
Can somebody tell me wich is the best adapter-library combination to make a secure client-server arduno based sensor?
enc28j60 O WIZNET5100? UIPEEthernet, Ethercard or EtherShield ?

The solution proposed is modify enc28j60.cpp about line 215

Enc28J60Network::sendPacket(memhandle handle)
.....
if( (readReg(EIR) & EIR_TXERIF) )
{
writeOp(ENC28J60_BIT_FIELD_CLR, ECON1, ECON1_TXRTS);
}
...
}

by

if( (enc28j60Read(EIR) & EIR_TXERIF) )
{
enc28j60WriteOp(ENC28J60_BIT_FIELD_SET, ECON1, ECON1_TXRST);
enc28j60WriteOp(ENC28J60_BIT_FIELD_CLR, ECON1, ECON1_TXRST);
enc28j60WriteOp(ENC28J60_BIT_FIELD_CLR, EIR, EIR_TXERIF);
}

It is correct???

Sorry for my English. Thanks again. Daniel