Re: IOC unusable if no ethernet interface at startup

[Markus Kristensson via Tech-talk <tech-talk at aps.anl.gov>]

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