TCP link not getting established between WIZnet812MJ and PC


Hello ,
I want to connect my embedded board ( having ethernet module812MJ ) to my PC which is in the same network .
I am not able to establish a link between PC amd ethernet board.
I did the following initialisation :

PC side : ip_addr =
gtw_Addr =
mac_addr = 00.30.67.BB.A9.28
subnet mask =

ETHERNET BOARD SIDE : ip_addr = ( provided by my n/w admin.)
gtw_addr = same as above
mac = ( I entered my own addr )
subnet mask = same as above

  1. first of all , I gave 8KB Tx and Rx memory to my socket S0.
  2. Configured socket 0 (S0) in " TCP WITH NO DELAYED ACKNOWLEDGMENT" mode . provided 502 as socket no. ( for the purpose of modbus communication over TCP/IP) to my socket 0 (S0 ).
  3. Gave “socket_open” command .
  4. Then by checking the SOCKET_INIT flag I configured socket 0(S0) in LISTEN mode.

After going through the above steps , I generated the TCP packet(with SYNC flag) using OSTINATO and monitored using WIRESHARK . But , i am not getting any reply from WIZNET module , nor i am able to see any kind of 3 way handshaking in flow graph .
So please help me out to solve the problem . Am i missing any initialisation of my module or there is some problem with my module itself .!!



First, Check the link led of the module.
And check ping request.
If no ping reply, check arp table of your PC using arp command
How to check arp table in dos command windows.
c:> arp -a
If the mac address of module is different from your configured address, arp-table should be updated by as below.
c:> arp -d

If there is no module ip’s mac address in arp-table, module ip address may be configrued another value.
Verify IP register & Mac Address Register.

If All cofiguration is correct, the module may be damaged. So, replace another module and retry test.



Thanking for your reply ,
I checked the link LED it is glowing fine , which means my ethernet connection is fine .
While trying to ping the module i was not getting any reply initially but , after a while Module suddenly replied to my ping (even its transmit LED glew 4 times when it replied as expected).
Then i gave the “arp -a” command and i sucessfully got my modules MAC address (that i had set in its MAC register ). That indicates my module is working fine .
After that i simply switched OFF my embedded board to which ethernet module is interfaced through SPI and then made it ON again. From this time onwards i am not getting any reply to my “ping” request .
I dont have any idea what could be the problem , pls help me out !!

                     Also it would be of great help if u could tell me about how to use " AX1 loopback test software " provided by wiznet (downloadable). will that software work with my embedded board or it requires some other Evaluation board..

                                                                                                                                            waiting for your reply ,


Hi, prashantkumar.

I don’t understand your situation exactly. After turn off the board and then turn on, ping test doesn’t work???

Please, explain more detailed.

And you can find AX1 manual in our web.

Best regards.


Hi prashantkumar,

I think something wrong may be there during communicating between your MCU and W5100 in WIZ812MJ.

Please write the value to some registers like SHAR, SIPR and so on, and read it out from them.
Unstable signals and timing can make this symptom.

I hope you will get the result what you want.