[etherlab-users] Limitations on Matlab Version - R2018b vs R2019a

[Moritz Schappler]

Hello Richard,

thanks for the quick reply. The output of `nm ecrt_support.o` showed a
potential reason: It is empty and the underlying file
rtw/blocks/EtherCAT/ecrt_support.c in the Matlab directory is also empty
(0 bytes).
It seems, as if the file should be used from
/usr/local/share/etherlab/src with 44kB, but Matlab takes the wrong
file. Matlab R2018b also has the empty file, but seems to not take it.
I installed Etherlab for both R2018b and R2019a in the same way, using
install.sh and setup_etherlab.m:
https://github.com/SchapplM/etherlab-examples/blob/master/SETUP_ETHERCAT.MD#entwpc
Perhaps setting up the directories for linking the Simulink project has
changed in R2019a, or I messed up the Matlab path without having noticed.
I re-tested on a different machine this time, though.

This duplicate 0B-file was already introduced in hg-commit 1146
(2018-02-08).
When I overwrite the 0B file with the full version in the Matlab dir, I
get similar errors. Instead of
>     new_2019a.o: In Funktion »new_2019a_step«:
>     new_2019a.c:(.text+0x15): Warnung: undefinierter Verweis auf
> »ecs_receive«
I get something like
>     ecrt_support.o: In Funktion »ecs_receive«:
>     ecrt_support.c:(.text+0xa0b): Warnung: undefinierter Verweis auf
> »ecrt_domain_process«
The output of  nm ecrt_support.o` now gives for R2018b and R2019a
>                  U calloc
>                  U clock_gettime
>                 [...]
>                  U ecrt_domain_data
>                 [...]
So the symbols are undefined ("U") also in the previous version R2018b.
Is it possible that the linker/compiler since R2019a is "stricter" and
now raises an error for the undefined references?

As for manually running the g++ command: Building fails with the same
error in R2019a and R2018b.
Therefore the path configuration only seems to work from within Matlab
(R2018b).
Up to now, the only manual adaptation to making the build process work
was symbolically linking the shared libraries in /usr/local/lib/ with
> $ ll /usr/local/lib/
> lrwxrwxrwx  1 root root    44 Apr  6 14:54 libethercat.so ->
> /usr/local/share/etherlab/lib/libethercat.so*
> lrwxrwxrwx  1 root root    42 Apr  6 14:56 libpdserv.so ->
> /usr/local/share/etherlab/lib/libpdserv.so
I attached the detailed logs.

In matlab-mex of the setup_etherlab.m I got the warnings
> Warning: You are using gcc version '7.5.0'. The version of gcc is not
> supported. The
> version currently supported with MEX is '6.3.x'. For a list of
> currently supported
> compilers see:
> https://www.mathworks.com/support/compilers/current_release.
which could also be related to handling of warnings/errors, but did not
pose a problem in R2018b for instance.

Thanks already for looking into this.

Viele Grüße
Moritz Schappler


On 06.04.20 13:18, Richard Hacker wrote:
> Hi Moritz
>
> I do not have Matlab > 2017 available to test, but I do not see a
> reason that ecs_*() symbols are not be found. They are defined in
> ecrt_support.c which is compiled and linked.
>
> Please go into the directory and supply me with the output of:
> cd /home/schappler/IMES/REPO/ethercat/etherlab-slaves/ixxa
> /new_2019a_etl_hrt
> nm ecrt_support.o
>
> Maybe try to compile the executable with (I just moved new_2019a.o
> forward):
> g++ -o ../new_2019a new_2019a_capi.o new_2019a.o new_2019a_data.o
> new_2019a_header.o rtGetInf.o rtGetNaN.o rt_nonfinite.o ecrt_support.o
> hrt_main.o -L/usr/local/lib  -lm -lpdserv -ldl -lrt -pthread
>
> Mit freundlichem Gruß
>
> Richard Hacker
>

-- 
__________________________________________________________
M. Sc. Moritz Schappler
Wissenschaftlicher Mitarbeiter und Gruppenleiter
Robotik & autonome Systeme

Gottfried Wilhelm Leibniz Universität Hannover
Institut für Mechatronische Systeme
An der Universität 1, Gebäude 8142 (Etage 1, Raum 108)
30823 Garbsen

Fon: +49 (0)511 762-4116
Fax: +49 (0)511 762-19976

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