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From Julian Feinauer <>
Subject AW: Reconnect of driver 2
Date Tue, 26 Mar 2019 15:10:09 GMT
Yes, I agree.
One of the few use cases of Java 8s default methods in interfaces...


-------- Ursprüngliche Nachricht --------
Betreff: Re: Reconnect of driver 2
Von: Christofer Dutz

Hi All,

I would agree that a void type and exceptions would allow a more fine-grained reporting of
what's going on.

Sort of:
- "Yeah ... I am a S7 400, but I don't support the S7-TIA protocol"
- "No connection under this number" (no connection possible)
- "You're not allowed to connect"
- "Invalid credentials"
- ...

Maybe we should do that ASAP, adding it to the API, but have it report "Not Implemented" for
now and to create JIRA tickets for the individual drivers ping implementations.


Am 26.03.19, 14:44 schrieb "Julian Feinauer" <>:

    Hi Gunther,

    thats really great to hear : )
    When I remember correctly the idea was...

    1. Extend the PlcConnection interface with a "ping()" method (Boolean? Throw Exception
if not possible?)
    2. Implement the Ping functionality for each plc with a sensible "operation" (not sure
what this could be for S7... read the SLZ or something?)
    3. Use this feature as "keep alive" e.g. for the PooledDriverManager

    does that make sense?


    Am 26.03.19, 13:55 schrieb "Gunther Gruber" <>:

        Sure I like to contribute. I guess by that you mean checking out the
        code and create a pull request with something working.

        I like your idear with the ping check. I will focus on implementing a
        function for the ping check, which can be reused later.


        > Hi Gunther,
        > good catch : )
        > In fact, the isConnected() implementation is currently not soo god.
        > In fact it checks if the underlying communication channel from netty is connected
(which does not know that it is disconnected yet, in your case).
        > We already had discussions to introduce a real "request" based implementation
like "ping()" which sends a request.
        > Furthermore, for your use case there is the PooledDriverManager which does implicitly
what you do... throws away a not working connection and issues a new one, if needed, but that’s
a separate topic.
        > I think we should spend some effort into this "ping" functionality.
        > Perhaps you can even assist with the implementation Gunther, what do you think?
        > Julian
        > Am 26.03.19, 11:19 schrieb "Gunther Gruber" <>:
        >      Put it another way, isConnected does not work as i expect it
        >      plcConnection.isConnected() returns true even when i disconnect the vpn
(maybe of some tcp/ip keepalive?)
        >      this is the snippet of code which i expect to work (instead of the thread
which reconnects ever 10 minutes)
        >      while (doCollect) {
        >        try {
        >          if (plcConnection == null || plcConnection.isConnected() == false) {
        >            plcConnection = initPLC(config.get(CONNECTION_KEY));
        >          }
        >        } catch (PlcConnectionException e) {
        >          logger.log(Level.WARNING, "error connecting with driver", e);
        >          plcConnection = null;
        >          incrementalSleep();
        >          break;
        >        }
        >        // Create a new read request:
        >        // - Give the single item requested the alias name "value"
        >        PlcReadRequest.Builder builder = plcConnection.readRequestBuilder();
        >      Gunther Gruber

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