[etherlab-users] etherlab-users Digest, Vol 104, Issue 1

[David Page]

Hi Paul,

The basic story is the EtherCAT slave hardware modifies the Ethernet frame
as it passes through each node, and then returns the modified frame back to
the host  -- essentially a token passing version of Ethernet. As such, the
use of standard hubs or switches will result in a packet storm. The bus
design assumes there is exactly one "normal" Ethernet host (at the master).
The slave hardware does support a UDP encapsulated mode which is useful for
hosts which cannot send and receive raw frames, but the above constraint
still applies.

It is possible with TwinCAT to talk over UDP (EtherCAT ADS protocol) to a
remote EtherCAT bridge (e.g. Beckhoff BK9000) which then has another port
dedicated to EtherCAT. The Etherlab master does not support ADS, though.

https://infosys.beckhoff.com/english.php?content=../content/1033/tcadscommon/html/tcadscommon_intro.htm&id=
https://www.beckhoff.com/english.asp?bus_terminal/bk9000_bk9050.htm


    - Dave Page





On Mon, Feb 1, 2016 at 6:00 AM, <etherlab-users-request at etherlab.org> wrote:

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>    1. Communicating with Ethercat over TCP/IP network (Paul Mulligan)
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> Message: 1
> Date: Sun, 31 Jan 2016 14:59:32 +0000 (UTC)
> From: Paul Mulligan <mulligan252 at yahoo.ie>
> To: "etherlab-users at etherlab.org" <etherlab-users at etherlab.org>
> Subject: [etherlab-users] Communicating with Ethercat over TCP/IP
>         network
> Message-ID:
>         <25812475.4467849.1454252372172.JavaMail.yahoo at mail.yahoo.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi,
> I've read that Ethercat packets can be sent over a network by packing them
> into UDP datagrams. Is it therefore possible to connect the Ethercat bus
> with slaves to a network and have the master controller pc not directly
> connected to the slaves but connected to the same network and hence
> transfer the Ethercat data to and from the slaves over the network? I
> assume the timing performance will be worse, but how is this achieved?
> Thanks
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