[Etherlab-users] Running a large number of slaves

Gavin Lambert gavin.lambert at tomra.com
Tue Mar 30 08:39:53 CEST 2021


Yes, it splits to multiple packets automatically.  Just be careful to not use more data than your cycle rate will allow.

Note that initialization and configuration of a large number of slaves is very slow by default, as it occurs in series.
The unofficial patchset changes this to occur in parallel (for groups at a time rather than the whole network, to avoid creating too many packets at once).


Gavin Lambert
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-----Original Message-----
From: Geller, Nir
Sent: Tuesday, 30 March 2021 1:23 am
To: Richard Hacker <ha at igh.de>; etherlab-users at etherlab.org
Subject: Re: [Etherlab-users] Running a large number of slaves

Hi,

Thanks for your reply.

You mean that in the case of a large amount of PDO data ( > 1500), a single invoke of ecrt_master_send(master) will result several frames sent out 1 after another?

Nir.

-----Original Message-----
From: Etherlab-users <etherlab-users-bounces at etherlab.org> On Behalf Of Richard Hacker
Sent: Monday, March 29, 2021 3:09 PM
To: etherlab-users at etherlab.org
Subject: Re: [Etherlab-users] Running a large number of slaves

EtherCAT and the master are not limited to the ethernet packet size.
EtherCAT frames are automatically divided into smaller ethernet packets as required. As long as you're not exceeding physical limits, (like sending ~1,5kb at a rate of 1kHz), you should be fine.

Physically EtherCAT can address ~64k slaves on a network.

On 2021-03-29 13:22, Geller, Nir wrote:
> Hi There,
>
> I'm trying to setup one ethercat master with a very large number of 
> ethercat slaves.
>
> The first obstacle I'm thinking about is a very large amount of data 
> sent over PDO each cycle, that will definitely exceed 1500 bytes.
>
> In order to address this issue I want to understand if it is possible 
> to send more than one frame each cycle?
>
> Another method could be using jumbo frames. Does the ethercat master 
> support that?
>
> Does anybody have practical experience with such a setup?
>
> Thanks,
>
> Nir.
>
>

Mit freundlichem Gruß

Richard Hacker

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