[etherlab-users] Timing measurements

[Florian Pose]

Hi Peter,

On Wed, Nov 25, 2009 at 03:05:02PM +0100, Peter van Knippenbergh wrote:
> I want to measure the latency of sending and receiving cyclic data, one of
> the slaves is a Beckhoff EL5101. I want to read a timing register every
> cycle. 
> 
> I want to map a register (not an object) to the process data, and therefore
> I tried to use the 3rd fmmu, but when going to OP, the ethercat master
> zero's the 3rd fmmu. 
> 
> Is there a easy way to get a timestamp in a user-space program for every
> cycle. It is ok for me if the communicated timestamp is an older tempstamp,
> because I want to use it for latency measurements.  

Just to be sure, that I understand you correctly: Does the slave
generate the timestamp and write it into a register and you just have to
collect it?

>From userspace, you can use the 'ethercat reg_read' command, but there's
no simple way to map it into process data, because there is no interface
to to this. But we could think about something like this...

-- 
Best regards,
Florian Pose

http://etherlab.org