[etherlab-users] Intermittent Large number of datagrams UNMATCHED

Graeme Foot Graeme.Foot at touchcut.com
Mon Jul 4 05:19:58 CEST 2016

The only time we've had issues like that has been due to either a dodgy network cable or an RJ45 plug getting a bit grubby.  First thing I usually do is unplug/replug all the plugs a few time to clean up the connections.  If it persists then I start looking for bad cables.

Another option is that there is an occasional noisy process causing noise on one of the links.

Once or twice (only on non-ethercat machines so far) we've had cables that were in drag chains wearing out, where it showed a problem when at a specific position of the drag chain.

You could track down if it's a problem with a link between two particular slaves by checking each slaves Link Lost Counter and CRC Bad Counter values.
- Lost Link Counter Register (0x0310:0x0313)
- RX Error Counter Register (0x0300:0x0307)

This link describes some of the diagnostics:

I think you can set the above registers to zero after the fieldbus is up and running, then you can check them if a problem occurs.

Haven't actually done it yet myself, so would be interested to see if it helps you.


-----Original Message-----
From: etherlab-users [mailto:etherlab-users-bounces at etherlab.org] On Behalf Of Henry Bausley
Sent: Saturday, 2 July 2016 5:56 a.m.
To: etherlab-users at etherlab.org
Subject: [etherlab-users] Intermittent Large number of datagrams UNMATCHED

We have a etherlab 1.5.2 kernel mode application running in xenomai
2.4.6 on Ubuntu 14.04.1 Desktop that will get on rare  occasions a large number of datagrams UNMATCHED.  It occurs at random times and relatively rarely but when it occurs it can result in disaster as we are running a large number of servos in torque mode.

For example we can run continuously for 5 days 24hours continuously then get a message like something below.

[591785.735172] EtherCAT WARNING 0: 616 datagrams UNMATCHED!
I am struggling as to where to look.  Is this something in our app or a known bug in the stack?

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