[etherlab-users] Time issues with EtherCAT functions

Graeme Foot GraemeF at touchcut.com
Thu Nov 8 02:32:22 CET 2012


Hi,

Do you have the latest EtherLab 1.5.1 release (with the RTDM updates)?  Do you have RTDM enabled in the ethercat master build?  (with the --enable-rtdm option.)

Check if you have any traps / syscalls in RTAI using the command "cat /proc/rtai/scheduler".  If you do, then the RTDM calls probably aren't configured correctly and you are losing realtime.


Regards,
Graeme.


-----Original Message-----
From: etherlab-users-bounces at etherlab.org [mailto:etherlab-users-bounces at etherlab.org] On Behalf Of Carlos Jiménez Leal
Sent: Thursday, 8 November 2012 05:00
To: EtherLAB Users
Subject: [etherlab-users] Time issues with EtherCAT functions

Hello,

I have some problems with the execution time of the EtherCAT functions 
in user space.
I'm using the version of the EtherLAB dated 06/11/2012, linux 2.6.29.5 
and RTAI 3.8.1 (with RTDM) for one cycle at 10kHz,
in a system with the following Beckohff modules: EK1100, EL2004, 
EL1004, EL4132, EL3102, 2xEL3356-0010, EL9510
on a 1.80GHz Intel Atom D525, with a Realtek 8139too

The cycle would be something like this:

cycle () {
	ecrt_master_receive ()
	ecrt_domain_process ()
	phases ()
	ecrt_domain_queue ()
	ecrt_master_send ()
	wait_next_cycle ()
}

I picked up the time it takes each and is far superior to that 
specified in the etherlab manual
(http://www.etherlab.org/download/ethercat/ethercat-1.5-6129a5f715fb.pdf)

			Retrieved 	Manual
Receive Master 		21micro-s 	2.2micro-s
Domain Process 	        11.5micro-s 	1micro-s
Domain Queue 		13.6micro-s 	1micro-s
Master Send 		14.3micro-s 	2.5micro-s

Besides occasionally one of them takes much longer, reaching 3_mili-s_ 
Master Receive
(attached compressed csv file data)

Anyone have any idea what could be happening?

Thank you in advance

-- 
Carlos Jiménez

ENCOPIM S.L.
C/. del Parc 5 (nau 13), P.I. Els Pinetons
E-08291 RIPOLLET (Barcelona)
Tel: (+34) 935 94 23 47
Fax: (+34) 935 94 64 15

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