Re: [RTnet-developers] Ethernet IP

[Glen W. <gl...@je...>]

Jan,

My basic concern was to keep the data flowing from the NIC to my program as
close to hard real time as possible. I know doing Linux calls can break hard
real time especially when I want to receive a UDP packet every 1ms.

The only thing Ethernet IP really gives you real time is optional support
for the Ethernet 1588 timing standard so you know what the jitter was in
receiving the packet over the Ethernet line. The 1588 support is not yet
implemented in opener. The rest is just a protocol for handling critical
data over TCP and UDP. Unfortunately, I have a device that needs to work on
Allen Bradley controllers which only support this real time protocol.

All I want to do is replace the Linux calls in networkhandler.c
(socket,bind,listen...) with RTAI real time calls.

Glen


On 9/28/10 4:39 PM, "Jan Kiszka" <jan...@we...> wrote:

> Am 28.09.2010 16:22, Glen Wernersbach wrote:
>> Hi Guys,
>> 
>> Woule you see any reason while we could not the open source Ethernet IP
>> project on top of RTNet?
>> 
>> Basically this builds on Linux stack but I want to run my stuff inside of it
>> real time. For that I need a real time driver for the ethenet that emulates
>> linux.
>> 
>> Ethernet IP project:
>> https://sourceforge.net/projects/opener/
> 
> I cannot asses what you could gain this way (do Ethernet IP devices
> provide real-time qualities via UDP/TCP?), but porting that stack over
> RTnet's UDP/TCP services should be feasible. The portability layer of
> opener looks rather thin and should be well covered by Xenomai's POSIX
> skin. However, our TCP implementation is still fresh, so you /may/ run
> into some of it current limitations. If you find such quirks, please let
> us know.
> 
> Jan
> 

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