[etherlab-users] Controlled by userspace application

Dipl.-Ing. (FH) Florian Pose fp at igh-essen.com
Wed Feb 6 09:34:16 CET 2008

Am 05. Februar um 18:05 schrieb Frank Werner:
> > On Mon, Feb 04, 2008 at 08:43:47PM +0100, Frank Werner wrote:
> >> Is there a possibility to determine the PDO mapping at runtime within
> >> the
> >> kernel module?
> > No, but this does not make sense in most cases, because you'll have to
> > know exactly, which PDO entries you want to use, anyway. The master
> > usually is the one, that defines the bus configuration and the mapping.
> Because the master defines the bus configuration I could ask the master
> about the configuration, or I am wrong?

Sorry, I meant the control module, not the master itself. If you're
writing a control application, you'll have to provide the I/Os you want
to use. You can query the current mapping via the sysfs files.

> The PDO for the EL2004 is at 0x7000:1. Is this adress static? You say the
> master defines this adress. What depends this adress on?

This PDO entry index is defined by the slave, and should be the same for
every EL2004. The indices used in your application have to match the
mapping inside the slaves. You can also change the mapping with the
ecrt_slave_pdo_mapping*() functions.

> Is there some documentation about the whole relation?

Yes, the EtherCAT standard... ;-)

> > Anyway, the next EtherCAT master release 1.4.0 will support you with
> > this task by supplying tools to create a valid configuration based on
> > the existing slaves and their current mapping.
> Will this be a kernel function or a userspace tool? Are there beta
> versions at this time?

Unfortunately not, but it will be a userspace tool.


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