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<== Date ==> <== Thread ==>

Subject: RE: Force TCP/IP reconnect from Asyn/Streamdevice
From: Mark Rivers <[email protected]>
To: Christoph Schroeder <[email protected]>, Torsten Bögershausen <[email protected]>, "[email protected]" <[email protected]>
Date: Tue, 23 May 2017 11:50:04 +0000
If you load an asyn record on this asyn port then you can use the CNCT (connect) field to force drvAsynIPPort to disconnect and reconnect the device.  This should be equivalent to restarting the IOC.  Have you tried this?  If it works then you just need to figure out some logic to tell when the device is hung up and write to this field twice, first with Disconnect and then with Connect.  Detecting when it has hung could be done with a longin record that increments each time you receive a message and then a calc record that processes periodically and checks to see if the longin record has stopped incrementing.

Mark

________________________________________
From: [email protected] [[email protected]] on behalf of Christoph Schroeder [[email protected]]
Sent: Tuesday, May 23, 2017 6:22 AM
To: Torsten Bögershausen; [email protected]
Subject: Re: Force TCP/IP reconnect from Asyn/Streamdevice

On 05/23/2017 12:26 PM, Torsten Bögershausen wrote:
>
>
> On 23/05/17 12:19, Christoph Schroeder wrote:
>> Hello,
>>
>>
>> On 05/23/2017 11:40 AM, Torsten Bögershausen wrote:
>>>
>>>
>>> On 23/05/17 10:53, Christoph Schroeder wrote:
>>>> Hi Torsten,
>>>>
>>>>
>>>> On 05/23/2017 10:40 AM, Torsten Bögershausen wrote:
>>>>> Which side does the retransmission ?
>>>>> The IOC ?
>>>>> The device ?
>>>> The device retransmits a package that the IOC already received
>>>> again and
>>>> again until it gives up. The IOC sends duplicate ACK. It seems the
>>>> acknowledge is ignored on the devices side.
>>>>> Now, well, it looks as if the reset was not processed by the IOC ?
>>>>> At least it didn't cause the TCP connection to be terminated, right ?
>>>> Right, netstat tells me the connection is still established, but there
>>>> is no flow of data anymore and the buffers are empty. The last
>>>> package I
>>>> reveived from the device is the TCP RST.
>>>>>
>>>>> Which OS are you using ?
>>>>> Which version of asyn ?
>>>>>
>>>> My tests where done with Debian 7 and Debian 8. The asyn version is
>>>> R4-30. The problem seems to be caused by a lower layer. I got the same
>>>> problem with a simple TCP client I wrote and even with netcat, so Asyn
>>>> isn't at fault here.
>>>
>>>
>>> You should be able to use the CONNECT_PER_TRANSACTION feature from asyn
>>> by using
>>> drvAsynIPPortConfigure("xx", "<host>:<port>[:localPort] http",0,0,0)
>>>
>>> (But I wonder if this helps, when your device seems to have such
>>> problems)
>> Thanks I will try this.
>>
>>>
>>> Another question:
>>>
>>> Is the IOC sending anything more to the device?
>>> And wait the response ?
>>> Why is it so quite on the line ?
>>> When the IOC polls the device, there should be some traffic coming out,
>>> I think.
>>> If there is nothing to be polled from the IOC, then it doesn't matter,
>>> if the underlying TCP connection is not working, half-broken or
>>> whatever.
>> The instrument sends unsolicited data starting directly after the
>> connections is established. There is no active communication from the
>> IOC to the device.
>
> That is sad to here, because then the "http" trick doesn't help us:
> The IOC will not send anything to the device.
> So there is no need to re-open the connection.
>
> Is there a chance to poll the device at all ?
>
>
> And/or:
> What does the device do, if you use your netcat test setup.
> and the connection is closed ?
> Will it accept a new one and behave better then on the old one ?

No chance for polling, communication on this port is read only. The data
is only send to the first client connected to the port. Closing the
connection and opening it again resp. rebooting the IOC or restarting
the client / netcat works fine until the error happens again. I observed
that the time until the error occurs depends on the number of TCP
packages send by the device which can be increased by configuring a
higher scan rate on the device. I think it's some kind of buffer or
counter overflow on the device which is reset with a new connection.


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Replies:
Re: Force TCP/IP reconnect from Asyn/Streamdevice Christoph Schroeder
References:
Force TCP/IP reconnect from Asyn/Streamdevice Christoph Schroeder
Re: Force TCP/IP reconnect from Asyn/Streamdevice Torsten Bögershausen
Re: Force TCP/IP reconnect from Asyn/Streamdevice Torsten Bögershausen
Re: Force TCP/IP reconnect from Asyn/Streamdevice Christoph Schroeder
Re: Force TCP/IP reconnect from Asyn/Streamdevice Torsten Bögershausen
Re: Force TCP/IP reconnect from Asyn/Streamdevice Christoph Schroeder

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