[etherlab-users] Use EtherCAT in Etherlab

Florian Pose fp at igh-essen.com
Fri Apr 24 09:29:18 CEST 2009


On Thu, Apr 23, 2009 at 09:59:22PM +0200, Andy Rohr wrote:
> I managed to run a minimal Etherlab System based on the bundle 1.6. I made 
> a "handcoded C application" using the C-API based on the given skeleton. 
> Now I would like to make use of the EtherCAT-Master and get some data from 
> EtherCAT slaves. The app_main.c has a function TaskStep where the cyclic 
> task is implemented. I this the point where I should use the 
> EtherCAT-master (doing things like in function "run" of the rtai_sample.c)? 
> How are EtherCAT-master and the realtime-task brought together without 
> using Simulink?

you could write a set of EtherCAT funkctions, for example

- ethercat_init(), which requests the master, does the bus configuration
  and master activation. Call this in TaskInit().

- ethercat_read(), which calls ecrt_master_receive() and
  ecrt_domain_process() and reads the EtherCAT inputs into the signal

- ethercat_write(), which writes process data from the signal tree into
  EtherCAT process image and then calls ecrt_domain_queue() and

Call there two in TaskStep(), and do your calculations in between.

In TaskExit(), you could call a function like ethercat_cleanup(), which
releases the master again.

I did it this way in a recent project and it works great.

Best regards,
Florian Pose


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