>> some of the competition's devices. Properly configured, our
>> remote serial ports could have lower latency than a native
>> 16x50 serial port.
>
> Excuse my ignorance, but how can you achieve "better" latency
> than "native" serial port? On local serial port the latency is
> as low as latency of driver stack (if any),
There's latency (mostly receive) in the UART -- especially if
the FIFO is enabled. For some cases the latency in the UART
exceeds the network latency. You can minimize the latency in
the UART by disabling the FIFO, but then you've got an awful
lot of interrupts to service.
> unlike remote serial port will have latency of: driver stack +
> network transport + serial server processing.
>> Here's a web page with a cute flash drag race animation
>> showing the latency testing results:
>>
>> http://www.comtrol.com/pub2/serialshootoutwp.asp.
>
> The data may be innacurate, especialy 5.35ms for the local
> serial port. I achieved oscilloscope measurable ~0.2ms
> response time on Win2k system on one project with ConnectTech
> BlueHeat and disabled FIFO.
Disabling the FIFO is the key. IIRC, our tests were all done
with the FIFO enabled because that's how our customers run
their native ports -- I presume because they've had problems
running native ports in one interrupt per byte mode.
> Maybe the 5ms on local port was measured with the card not
> transmitting immediately if FIFO is not full.
The latency on the local port is mostly in the receive FIFO. If
the recieve data stops, there's a timer that has to timeout
before a receive interrupt is generated.
--
Grant Edwards grante Yow! My Aunt MAUREEN was
at a military advisor to IKE &
visi.com TINA TURNER!!
Reply by rziak●August 17, 20052005-08-17
> some of the competition's devices. Properly configured, our
> remote serial ports could have lower latency than a native
> 16x50 serial port.
Excuse my ignorance, but how can you achieve "better" latency than
"native" serial port ? On local serial port the latency is as low as
latency of driver stack (if any), unlike remote serial port will have
latency of: driver stack + network transport + serial server
processing.
The data may be innacurate, especialy 5.35ms for the local serial port.
I achieved oscilloscope measurable ~0.2ms response time on Win2k system
on one project with ConnectTech BlueHeat and disabled FIFO.
Maybe the 5ms on local port was measured with the card not transmitting
immediately if FIFO is not full.
Reply by Grant Edwards●August 17, 20052005-08-17
On 2005-08-17, rziak <news@ziak.com> wrote:
> I have recently worked with B&B's ESO901 serial server. It has
> also the virtual serial port (Windows) but it seems they have
> latency problems (like 250ms on the serial loopback),
That seems to be a pretty common problem. When I worked at
Comtrol, we put a fair bit of effort in to keeping latency to a
minimum, and our products were an order of magnitude faster the
some of the competition's devices. Properly configured, our
remote serial ports could have lower latency than a native
16x50 serial port.
Here's a web page with a cute flash drag race animation showing
the latency testing results:
http://www.comtrol.com/pub2/serialshootoutwp.asp.
There's a table of results on the page, and a link to download
a whitepaper explaining the testing methodology and the
benchmark program.
> so I had to write the code which does access the serial port
> using sockets. B&B's technical support on this issue was close
> to none, but I found out they licensed the product from
> Passport Networks http://www.passportnetworks.com/ and these
> guys were quite helpful. If you will be buying PNI's ESport,
> ask for their IPSSP library.
--
Grant Edwards grante Yow! Catsup and Mustard
at all over the place! It's
visi.com the Human Hamburger!
Reply by Ross Marchant●August 17, 20052005-08-17
"shoaibali11" <shoaib.ali@and-or.com> wrote:
> Hi everyone!
>
> My requirement is very simple.
> I have serial port access on my product
We have used the moxa ne-4110s successfully
Ross
Reply by tguclu●August 17, 20052005-08-17
>I have recently worked with B&B's ESO901 serial server. It has also the
>virtual serial port (Windows) but it seems they have latency problems
>(like 250ms on the serial loopback), so I had to write the code which
>does access the serial port using sockets. B&B's technical support on
>this issue was close to none, but I found out they licensed the product
>from Passport Networks http://www.passportnetworks.com/ and these guys
>were quite helpful. If you will be buying PNI's ESport, ask for their
>IPSSP library.
>
>I use the Moxa to switch btw RS-232/Ethernet.
may be u might get interested ?
This message was sent using the comp.arch.embedded web interface o
www.EmbeddedRelated.com
Reply by rziak●August 17, 20052005-08-17
I have recently worked with B&B's ESO901 serial server. It has also the
virtual serial port (Windows) but it seems they have latency problems
(like 250ms on the serial loopback), so I had to write the code which
does access the serial port using sockets. B&B's technical support on
this issue was close to none, but I found out they licensed the product
from Passport Networks http://www.passportnetworks.com/ and these guys
were quite helpful. If you will be buying PNI's ESport, ask for their
IPSSP library.
Reply by Eric●August 17, 20052005-08-17
Check out the Lantronix Xport
Reply by Grant Edwards●August 17, 20052005-08-17
On 2005-08-17, shoaibali11 <shoaib.ali@and-or.com> wrote:
> My requirement is very simple. I have serial port access on
> my product but I want ot interface it with PC via ethernet.
> I actually want to connect say 5-10 of my products to PC via
> ethernet. From product side, what I want is that, when I
> send a byte out of serial port ; a device(like EM-202 by
> tibbo) connected to the serial port sends that byte over
> ethernet appending required headers/footers. Similarly from
> PC side, when I send a byte using TCP(may be socket
> programming), the connected device(like EM-202) sends that
> byte over serial link. Can EM-202 do this for me ?
Ask the poeple who sell it.
> How ? If somebody already has done this , then, please help
> me. thanx
A former employer of mine has a whole line of products that do
what you want. They devices range from models with 1 serial
port to models with 32 serials ports. From the host end, the
ports can be accessed via TCP sockets or you can install a
device driver for Linux or Windows that make the ports
accessible as "normal" serial ports (/dev/ttyXX under Linux or
COMXX under Windows).
http://www.comtrol.com/
--
Grant Edwards grante Yow! Did an Italian CRANE
at OPERATOR just experience
visi.com uninhibited sensations in
a MALIBU HOT TUB?
Reply by shoaibali11●August 17, 20052005-08-17
Hi everyone!
My requirement is very simple.
I have serial port access on my product
but I want ot interface it with PC via ethernet.
I actually want to connect say 5-10 of my products to PC via ethernet.
From product side, what I want is that, when I send a byte out of seria
port ;
a device(like EM-202 by tibbo) connected to the serial port sends tha
byte over ethernet
appending required headers/footers. Similarly from PC side, when I sen
a byte
using TCP(may be socket programming), the connected device(like EM-202
sends that
byte over serial link. Can EM-202 do this for me ? How ? If somebod
already has done
this , then, please help me. thanx
shoaib.ali@and-or.com
This message was sent using the comp.arch.embedded web interface o
www.EmbeddedRelated.com