Multi-drop network
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Multi-drop network
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Ted
Guest
Posted: Mon Nov 07, 2005 4:57 pm    Post subject: Multi-drop network Reply with quote
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)


Anyone got any ideas? CANBus comes close, but isn't fast enough.

Cheers
TW
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Ted
Guest
Posted: Mon Nov 07, 2005 5:15 pm    Post subject: Re: Multi-drop network Reply with quote
Forgot to mention that it should have a range of around 5 metres.

TW
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PeteS
Guest
Posted: Mon Nov 07, 2005 5:15 pm    Post subject: Re: Multi-drop network Reply with quote
A possibility is SPI (Serial Peripiheral interface).

Your PC104 will need a separate line for each device select (addressing
done in hardware, not part of the data protocol). It's a snap to
implement in hardware.

Cheers

PeteS
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Tauno Voipio
Guest
Posted: Mon Nov 07, 2005 11:50 pm    Post subject: Re: Multi-drop network Reply with quote
Ted wrote:
Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
4. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)

So you are looking for > 30 Mbits/s net. It means
a wavelength of less than 10 meters for the bit rate
(in practical cables less than 7 meters).

The only PC network technologies coming close
to the speed are 100 Mbit/s Ethernet and Firewire,
but both need hubs.

IMHO, the speed requirement makes it pretty difficult
to create a multi-drop network with the requested
cable lengths.

--

Tauno Voipio
tauno voipio (at) iki fi
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Grant Edwards
Guest
Posted: Tue Nov 08, 2005 1:15 am    Post subject: Re: Multi-drop network Reply with quote
On 2005-11-07, Ted <ted.wood@sortex.com> wrote:
Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)

How about 10base2 Ethernet?

There seem to be plenty of PC104 cards available.

http://www.dpie.com/pc104/pia3610.html
http://pc104.winsystems.com/products/pc104/pcmne2000bnc.html
http://www.ampltd.com/prod/azlan.html

--
Grant Edwards grante Yow! My face is new, my
at license is expired, and I'm
visi.com under a doctor's care!!!!
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Anton Erasmus
Guest
Posted: Tue Nov 08, 2005 1:15 am    Post subject: Re: Multi-drop network Reply with quote
On 7 Nov 2005 02:57:21 -0800, "Ted" <ted.wood@sortex.com> wrote:

Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)


Anyone got any ideas? CANBus comes close, but isn't fast enough.


You might be able to do it with a high speed card capable of SDLC.
This is a token passing protocol, and your devices need to be
connected in a ring. Infineon and others have devices that can handle
this protocol. AFAICR they should be able to handle the data rate.

Regards
Anton Erasmus
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Heinz-Jürgen Oertel
Guest
Posted: Tue Nov 08, 2005 1:15 am    Post subject: Re: Multi-drop network Reply with quote
Ted wrote:

Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)


Anyone got any ideas? CANBus comes close, but isn't fast enough.

Don't like to offend, but did you make your calculations on the best use of

CAN? I mean CAN should not be used for large data junks and repeating
transmission. If used in the suggested event driven communication mode,
sending data only if information changes, it saves a lot of bandwith.

Regards
Heinz
--

with best regards / mit freundlichen Grüßen

Heinz-Jürgen Oertel
+===================================================================
| port GmbH phone +49 345 77755-0
| Regensburger Str.7b fax +49 345 77755-20
| D-06132 Halle/Saale mailto:service@port.de
| Germany http://www.port.de
| CAN Wiki http://www.CAN-Wiki.info/
| ETHERNET Powerlink http://www.epl-tools.com
| Newsletter: http://www.port.de/register.html
+===================================================================

Merokok dapat menyebabkan kanker, serangan jantung,
impotensi dan gangguan kehamilan dan janin.
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Guest
Posted: Tue Nov 08, 2005 7:19 am    Post subject: Re: Multi-drop network Reply with quote
Are you sure you want PC104 and not PC104+? The PC104 with an ISA bus
is going to be a limitation. At least with PC104+ you get a PCI bus.

I've used some of Sealevel.com's PC104 equipment for RS422 on a 20+
node network. They have a new product that supports 10M bps, but not
quite your 3Mbyte/sec. ACB-104.ULTRA PC/104-Plus RS-232, RS-422,
RS-485, RS-530, RS-530A, V.35 Synchronous Serial Interface (uses
Z16C32)

http://www.sealevel.com

If you can changed to PC104+ with a PCI interface instead of PC104
with an ISA bus, then General Standards.com might have a product that
gets close to what you want (only 10Mbits/sec..

The PC104P-SIO4B is a four channel full-duplex RS-422/485 serial
board. Each channel can operate up to 10Mbits/s. Up to 32 Kbytes of
FIFO buffering for both transmit and receive (256 Kbytes Total FIFOs)
data on each channel provides for a smooth and efficient interface
between the serial interfaces and the host computer. This product is
based on the Zilog© Z16C30© high speed Integrated Universal Serial
Controller (USC) which supports Asynchronous, Isochronous, Bisync,
Monosync, HDLC, SDLC, External Sync and Nine-Bit protocols. The USC
chip provides full duplex operation with baud rate generators, digital
phase-locked loop for clock recovery and a full duplex DMA interface.
NOTE: some of the documentation for this product is still being
updated, so links below may be to documents with similar operation.

http://www.generalstandards.com/view-products.php?product=PC104P-SIO4B&formfactor=&function=Serial


On 7 Nov 2005 02:57:21 -0800, "Ted" <ted.wood@sortex.com> wrote:
Quote:
I'm looking for a networking technology with the following requirements
1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)
Anyone got any ideas? CANBus comes close, but isn't fast enough.
Cheers TW
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Donald
Guest
Posted: Tue Nov 08, 2005 7:21 am    Post subject: Re: Multi-drop network Reply with quote
Grant Edwards wrote:
Quote:
3. Transfer rate > 3MBytes/s = 30Mbits/S
How about 10base2 Ethernet? = 1Mbytes/S

Dosen't cut it.
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Grant Edwards
Guest
Posted: Tue Nov 08, 2005 7:34 am    Post subject: Re: Multi-drop network Reply with quote
On 2005-11-08, Donald <donald@dontdoithere.com> wrote:
Quote:
Grant Edwards wrote:
3. Transfer rate > 3MBytes/s = 30Mbits/S
How about 10base2 Ethernet? = 1Mbytes/S

Dosen't cut it.

Doh. I misread the OP's requirement as 3Mbits/s.

--
Grant Edwards grante Yow! QUIET!! I'm being
at CREATIVE!! Is it GREAT
visi.com yet? It's s'posed to SMOKEY
THE BEAR...
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Paul Carpenter
Guest
Posted: Tue Nov 08, 2005 10:23 am    Post subject: Re: Multi-drop network Reply with quote
On Monday, in article
<GZmdnXf_jYktYPLenZ2dnUVZ_sOdnZ2d@forethought.net>
donald@dontdoithere.com "Donald" wrote:

Quote:
Grant Edwards wrote:
3. Transfer rate > 3MBytes/s = 30Mbits/S
How about 10base2 Ethernet? = 1Mbytes/S

Dosen't cut it.

Considering ISA is classed as a 2MBytes/sec bus (as PC104 = ISA), how are
you going to get 3MBytes/sec across?

Personally at these rates either use as someone else has said PC104plus for
higher bandwidth.

Then consider 100baseT network and accept the uncertainty factor, or split
your 20 nodes into sub-networks of smaller sizes each with its own 'network'
interface. Your network interface then can be RS422/485, or other means.

Personally I think you are trying to "fit a quart into a pint pot".

--
Paul Carpenter | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.gnuh8.org.uk/> GNU H8 & mailing list info
<http://www.badweb.org.uk/> For those web sites you hate
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Ted
Guest
Posted: Tue Nov 08, 2005 3:40 pm    Post subject: Re: Multi-drop network Reply with quote
Heinz-Jürgen Oertel wrote:

Quote:
Don't like to offend, but did you make your calculations on the best use of
CAN?

Yes. Its an absolute requrement that we be able to transfer 2MByte of
data in under a second.

TW
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Ted
Guest
Posted: Tue Nov 08, 2005 3:42 pm    Post subject: Re: Multi-drop network Reply with quote
Grant Edwards wrote:

Quote:
How about 10base2 Ethernet?

Grant

We are currently using 10Base 2. It is pretty much an obsolete
technology these days. Most of the major manufacturers have obsoleted
their PHYs for it. Designing it into a product that will have a life of
5+ years doesn't seem like a safe decision right now.

Cheers
TW
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Rene Tschaggelar
Guest
Posted: Tue Nov 08, 2005 4:31 pm    Post subject: Re: Multi-drop network Reply with quote
Ted wrote:
Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)


Anyone got any ideas? CANBus comes close, but isn't fast enough.

With simple selfmade hardware this specification is
doable. As physical medium choose RS422, RS485, LVDS,
all on twisted pair. A separate clock line allows
synchroneous hardware. As serializer/deserializer,
have a look at CPLDs & Serdes.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
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Meindert Sprang
Guest
Posted: Tue Nov 08, 2005 4:59 pm    Post subject: Re: Multi-drop network Reply with quote
"Ted" <ted.wood@sortex.com> wrote in message
news:1131361041.613821.185530@o13g2000cwo.googlegroups.com...
Quote:
I'm looking for a networking technology with the following requirements


1. Multidrop.No hub/router/switch
2. Up to 20 nodes
3. Transfer rate > 3MBytes/s
5. Supported by an off-the-shelf PC104 type card for an industrial PC
(master)
5. Easy to implement in HW (slave)

Since you don't specify a bus width, have you considered SCSI?
Years ago I saw an article in DDJ where somewone had networked a couple of
PCs through SCSI.
I know the SCSI standard does not support more that 8/16 devices, but you
could use the SCSI hardware to implement your own protocol and thus address
more that 16 devices.

Meindert
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