On Sun, 15 Mar 2015, Karlsson & Wang wrote:
Date: Sun, 15 Mar 2015 20:03:56 +0100
From: Karlsson & Wang <nicklas.karls...@karlssonwang.se>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Ethernet!
You are right, there are more bandwidth but there may be collisions. I do
not now about the switches but for old HUBs the full bandwidth can't be used
because of collision and there actually is a statistical upper limit below
maximum capacity. Worst case delay is of course higher.
There are no collisions in a real time Ethernet system, for example RT-Net
uses TDM so each device gets its own time slot. Ethercat allows a higher
update rate for situations where many devices have small amounts of data
since it eliminates the inter-packet delays but GigE has higher useable
bandwidth if the amount of data is larger.
For ethercat full bandwidth can be utilized without collisions even if there
are several devices. I have chosen ethernet because I think it will be good
enough, it is available in almost all computers and there are cheap
development boards available with 100Mbit ethernet.
I think Ethercat make a lot of sensors for manufacturers since there are no
collisions or statistics involved so they could prove the system work
correct but for a machine built to be used by yourself this proof is rather
useless.
Nicklas Karlsson
On Sun, 15 Mar 2015 10:58:38 -0700 (PDT)
"Peter C. Wallace" <p...@mesanet.com> wrote:
On Sun, 15 Mar 2015, Karlsson & Wang wrote:
Date: Sun, 15 Mar 2015 18:34:13 +0100
From: Karlsson & Wang <nicklas.karls...@karlssonwang.se>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: Klemen Dovrtel <klemen_dovr...@yahoo.com>,
"Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Ethernet!
I have tried Ethernet and it works but if you connect to a switch, hub or
similar with more devices there may of couse be real time problems. Ethernet
is cheap and readily avaiable although Ethercat I expect to be better if the
extra bandwidth is needed.
Nicklas Karlsson
Actually regular Ethernet GigE is better for bandwidth than Ethercat
(AFAIK EtherCAT is limited to 100 mbit by current hardware)
On Sat, 14 Mar 2015 18:09:24 +0000 (UTC)
Klemen Dovrtel <klemen_dovr...@yahoo.com> wrote:
I am also interested in rt ethernet. Can you please point out which
instruction are these,
RegardsKlemen
On Friday, March 13, 2015 3:54 PM, sam sokolik <sa...@empirescreen.com>
wrote:
I still cannot believe that it is possible. I have been testing 2.7+
uspace for a while now. It defiantly opens up options.
Building the latest rt-preemt using peters instructions and .config made
the latency on this laptop much much better. I am running a 2khz servo
thread for a day now.
http://electronicsam.com/images/KandT/testing/0313150923b.jpg
Realtime communication over Ethernet is just darn awesome!
I would not use a laptop for normal machine running - but for developing
systems - it sure will be nice.
Thanks Peter, Micges, Jeff and everyone else that has made this a reality.
sam
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Peter Wallace
Mesa Electronics
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Mesa Electronics
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