I am trying to send FINS commands via UDP from a PC (C # .NET) to an Ethernet Ethernet module (Omron), but does not receive a response from the PLC and has no idea where I can start troubleshooting.
The PLC has a very simple ladder logic: If the DM100 has the value #0001 , then output 101.00 . (Here, “Trigger” is just the symbol name for the D100 memory area, and “Exit” is the output symbol 101.00 ) 
Then I wrote a C # snippet that runs the FINS "Write Area Memory" command, which has a command code of 01 02 , followed by the start address, the number of items to write, and data. The C # code must write the value # 0001 to the PLC area D100 in order to enable ON at 101.00 .
[remote code that does not work].
Exit 101.00 does not work, and I get no exceptions. I made sure of the following:
- The port, node and address are configured correctly, as confirmed in "Work Online" in the CX-Programmer. I also check each IP to make sure that the nodes are connected.
- The
UdpClient code UdpClient valid since I wrote a very simple server / client code that successfully sends and receives packets. - Ladder logic has no problems. I moved the ladder to the PLC and checked Work Online in monitor mode and set the value to
D100 manually.
I suspect that there is an error in the fins_cmnd array, but as can be seen from my code, I commented on as much as possible detailed information about each value; I can’t find anything. I suspect that I cannot parse the hex code correctly, but then again, I have no exception for the manual.
I have no idea where or how I can troubleshoot. Hope someone here with FINS programming or PLC experience can help me.
[ANSWER]
Thanks to Porge for the link - it made me deal with the problem. After a couple of trails, finally make it work. Below is the working code.
string SERV_IP_ADDR = "192.168.250.1"; const int FINS_UDP_PORT = 9600; byte[] sendPacket = new byte[] { // Full UDP packet: 80 00 02 00 00 00 00 05 00 19 01 02 82 00 64 00 00 01 00 01 // Header 0x80, //0.(ICF) Display frame information: 1000 0001 0x00, //1.(RSV) Reserved by system: (hex)00 0x02, //2.(GCT) Permissible number of gateways: (hex)02 0x00, //3.(DNA) Destination network address: (hex)00, local network 0x00, //4.(DA1) Destination node address: (hex)00, local PLC unit 0x00, //5.(DA2) Destination unit address: (hex)00, PLC 0x00, //6.(SNA) Source network address: (hex)00, local network 0x05, //7.(SA1) Source node address: (hex)05, PC IP is 192.168.250.5 0x00, //8.(SA2) Source unit address: (hex)00, PC only has one ethernet 0x19, //9.(SID) Service ID: just give a random number 19 // Command 0x01, //10.(MRC) Main request code: 01, memory area write 0x02, //11.(SRC) Sub-request code: 02, memory area write // PLC Memory Area 0x82, //12.Memory area code (1 byte): 82(DM) // Address information 0x00, //13.Write start address (2 bytes): D100 0x64, 0x00, //15.Bit address (1 byte): Default 0 0x00, //16.No. of items (2 bytes): only one address which is D100 0x01, // Write Data 0x00, //18.Data to write (2 bytes): value is 1 0x01, }; UdpClient client = new UdpClient(); //create a UdpClient instance try { client.Send(sendPacket, sendPacket.Length, SERV_IP_ADDR, FINS_UDP_PORT); } catch (SocketException se) { Console.WriteLine(se.ErrorCode + ": " + se.Message); } client.Close();