Modbus TCP Slave via dynamic DNS

Engineering 🇬🇧
tcave42
2021-02-23
2021-02-24

  • tcave42 - 2021-02-23

    Is it possible to run an Modbus TCP connection to a device that is offsite on a different network via a dynamic DNS like for example DuckDNS?

     

  • i-campbell

    i-campbell - 2021-02-23

    In Library Manager, add the Net Base Services library.
    In your program declare a variable of type NBS.ResolveHostname
    Call this instance to resolve the hostname.

     

    Last edit: i-campbell 2021-02-23

    • tcave42 - 2021-02-23

      thank you for your reply, I'm still not having any luck, could you make an example?

       

      • i-campbell

        i-campbell - 2021-02-24 
        PROGRAM PLC_PRG
VAR
    instResolveHostname : NBS.ResolveHostname;
    xResolved: BOOL;
    xResolve: BOOL;
    myIP: NBS.IPv4Address;
    myIPInterface : NBS.IIPAddress := myIP;
    TheIPYouAreLookingFor: UDINT;
END_VAR

instResolveHostname(
    xExecute:= xResolve, 
    udiTimeOut:= 10_000_000, //10sec timeout
    xDone=> xResolved, 
    sHostname:= 'www.codesys.com', 
    itfIPAddress:= myIPInterface
    );

TheIPYouAreLookingFor := myIP._udiIPAddress;
         

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