Re: IOC unusable if no ethernet interface at startup

[Torsten Bögershausen via Tech-talk <tech-talk at aps.anl.gov>]

Hej Markus,

If I set this line in my shell-script:

 export EPICS_PVAS_INTF_ADDR_LIST=127.0.0.1

I can start the IOC.

It will give you a warning:
No server broadcast addresses found or specified - empty address list!
which is nice

/Torsten



> On 27 maj 2021, at 14:44, markus.kristensson at nuclear.lu.se wrote:
> 
> Hej Torsten,
> Hope you are doing well!
> 
> Interesting. Since I use PyEpics/PyQt for the GUI that would probably be a solution for me. However, I do use e3, but I suspect that updating this make-file would be feasible herein also?
> 
> For future reference, if pvaccess was to be used on an offgrid device, could a possible solution be to create a virtual dummy interface on the RPi?
> 
> Cheers from Skåne,
> Markus
> 
> 
> 
> 2021-05-27 08:41 skrev Torsten Bögershausen:
>> Hej Markus,
>> as far as I know:
>> The "IOC not probably working when we don't have any physical network
>> interfaces" is only there for pvacess.
>> pvaccess uses a different way than channel access
>> (to detect interfaces which the ca/pv binds to).
>> Looking from the EPICS community point of view, it seems as if this
>> "networkless IOC" is rarely used.
>> In your case it may help to disable the pvaccess completely.
>> I have something like this in my Makefile:
>> ifdef BASE_7_0
>> ethercatmc_DBD += PVAServerRegister.dbd
>> ethercatmc_DBD += PVACommonRegister.dbd
>> ethercatmc_DBD += softIocPVA.dbd
>> ethercatmc_DBD += registerChannelProviderLocal.dbd
>> endif
>> HTH, greetings to Lund
>> /Torsten
>> On 5/27/21 12:04 AM, Markus Kristensson via Tech-talk wrote:
>>> Hi again,
>>> I've investigated the problem further. It turns out that I was too quick in judging that the IOC was starting up more or less correctly even when the ethernet cable was not plugged in. The reason for that conclusion was two-fold: 1. I ran the RPi in headless mode without any monitor connected. 2. The RPi did respond to change in some hardware, namely me changing a physical switch between two states. The response of changing the switch was seen in the opening/closening of a relay. As already stated, the response was very slow (sometimes around 10 s). What bugged me was that the same relay card did not open when a number of other DI:s received signal.
>>> With a monitor connected I now realise that the IOC is actually NOT starting correctly when the ethernet cable is unplugged. The error is a BaseException with "No (specified) network interface(s) available". Interestingly, the plc (I run the ecmc-module) which handels the logic starts up briefly before the IOC startup is terminated. This gives enough time to read the input from the switch and to open up the relay, but not enough time for the other inputs to respond because of the logic using hysteresis (this is a solution for dealing with 14 cooling rooms and 2 cooling machines etc...). The slow responding time of the switch (max around 10 s) should then basically be related to the restart time of the IOC which I've configured using systemd to 10 s.
>>> So, some things better understood, but my basic problem still remains. Do you have any suggestions of how I can resolve the problem of starting an IOC without it being connected to any network? I suspect I need to modify the startup script of the IOC, e.g. specifying EPICS_CA_ADDR_LIST to localhost. So far I have not been successful with such modifications.
>>> Cheers,
>>> Markus
>>> 2021-05-26 20:31 skrev Markus Kristensson via Tech-talk:
>>>> Hi,
>>>> I have configured a Raspberry Pi 3 Model b+ to autostart and launch an
>>>> IOC. The startup works fine if the RasPi is connected via ethernet to
>>>> another computer. If the lan is not connected at startup, the IOC is
>>>> basically unusable, responding to certain inputs, but extremely slow.
>>>> If the ethernet cable is plugged back in, the responsiveness of the
>>>> IOC is back to normal.
>>>> The RasPi will normally be connected to the other computer, but it is
>>>> not necessarily so. I only need to control and access the IOC on the
>>>> RasPi locally (i.e. on the Raspberry Pi itself). Do you have any
>>>> suggestions how to proceed?
>>>> Cheers,
>>>> Markus Kristensson