[etherlab-users] Assigning Dynamic PDOs

[Florian Pose]

Hi,

On Wed, May 05, 2010 at 05:08:15PM +0200, Fabian Herb wrote:
> "ethercat slave -v" contains "Enable PDO Assign: no", but the documentation of 
> the slave (Beckhoff EL6751) could be understood in a way where PDO assignment 
> should be allowed, so maybe you're right. Perhaps I should contact Beckhoff on 
> that matter.

ok, it is an EL6751. This slave is quite complex. It generates its PDO
mapping once you write down the 0x8000 object. You can store the
configuration afterwards, so that the PDO mappings can be read out once
in PREOP.

> > A few comments to your log file:
> > 
> > - Why do you call ecrt_master_slave_config() for the same configuration
> >   hundereds of times?
> 
> This is caused by the architecture of my application. To simplify things: I 
> have functions which take a slave address as parameter. Is there a problem in 
> calling ecrt_master_slave_config() so often? I could probably cache the result 
> easily.

No problem. I was just wondering. ecrt_master_slave_config() will always
return the existing configuration, if called twice.

> > - When using ecrt_slave_config_pdo_*_add() you should first call
> >   ecrt_slave_config_pdo_*_clear(), to be sure, that no objects are
> >   mapped/assigned before.
> 
> I'm not sure if I already tried this out, so I'll do that. Thanks!

This is not the problem here, but you should call 'clear' to be shure,
that there is nothing mapped/assigned before.

-- 
Best regards,
Florian Pose

http://etherlab.org