Re: Data transfer for real time analysis

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From: Pini (pinit_at_ee.bgu.ac.il)
Date: 04/27/04 

Date: Wed, 28 Apr 2004 00:35:52 +0200

The system is developed for academic research of biological signals.

Each channel sampling rate is 25KHz. Each data frame holds 25 samples. The
data will be processed in frames.
I' planning to use a PC with 4 CPU's. One fore handling the data
communication and memory allocation, one for handling the HD storage and the
2 last CPU will be for number crunching. A second alternative is to use a
PCI board with multiple DSP for data analysis and the PC will do the data
fusion from all the channels for closing the loop (and data storage).
We can use FPGA at the sub-units if required.
We can not afford any data package loss.
Regarding the selection of the communication protocol:

TCP/IP:
What will be worst the latency of each channel if I use TCP/IP Hub
(100MBit/sec
or 1000MBit/sec)?
Will the use of windows CE guaranty the Ethernet frame overall latency?
(Did someone tried the real-time TCP/IP extension from:
http://www.vci.com/products/windows_embedded/rttcpip.asp )

I2C:
What HW should I use on the PC side?
What about SMBus? What should I use on the PC side?

USB:
I can use the USB protocol but I have a latency of 1msec (can I reduce this
latency)?
What is the USB Hub latency?

  Regards
    Pini

‏‏"Pini" <pinit@ee.bgu.ac.il> כתב בהודעה
news:c6h98p$3jm$1@news.iucc.ac.il...
> hi,
>
> We are planning a data acquisition system with 4-12 sub units. Each sub
unit
> produce data of 25MBit/sec. The distance between the boxes and computer is
> about 2 meters.
> I'm willing to transfer and analyze the data in real-time. I'm willing to
> close a control loop in 1-5msec (I. wish 100usec ......).
> What is the recommended serial protocol?
> The sub units will be in-house made the host computer for data analysis
and
> storage will be a PC (probably with raid HD).
> What communication HW should I use in my sub units?
> What communication HW should I use in the PC?
>
> Regards
> Pini
>
>

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