Re: EMC compatable computers

[John Sheahan <jrsheahan-at-optushome.com.au>]

The observation that ethernet does not always need a protocol
stack is useful, and also applies to USB I suspect.

vertainly ethernet is cheap and transformer isolated - which seems 
appropriate in the environment.

firewire 2 is nice and optical - and you probably don't need 
the membership to use it.  but GbE would seem more logical if 
fibre is desired.

john



On Sat, Jan 11, 2003 at 12:14:55AM -0500, Matt Shaver wrote:
> 
> On Friday 10 January 2003 12:20 pm, Phil Wilshire wrote:
> > HI All
> >
> > I would think that Firewire would make a better option for a bus driver
> > servo board.
> > Any comments ???
> > If you want a USB solution the 5272 Coldfire embedded system should work
> > here.
> > Again any comments ??
> 
> I don't know enough to comment whether 1394 has latency or frame rate 
> problems like USB, but there are even bigger non-technical stumbling blocks:
> 
> 1. The development kits I've seen cost $1500-$2000. See:
> http://www.emjembedded.com/cgi-bin/america/setframe.cgi?spec+MDR
> 
> 2. Firewire development is effectively a closed process controlled by the 
> 1394 Trade Association. Realistic participation requires becoming a member. 
> Membership fees start at (you can see this coming, can't you...) $4000... 
> every year!
> 
> The PPMC should be viable for a long time in desktop PCs with PCI parallel 
> port add-in cards. If you want to develop a high speed serial controller, I 
> think the best option is Ethernet. I don't mean a complete TCP/IP network 
> device, more like a dedicated 100BaseT NIC connected to an embedded ethernet 
> equipped servo controller through a crossover cable. The communications 
> protocol would be raw frames (there's integrated hardware CRC checking for 
> each frame). Inexpensive prototyping materials are widely available. As an 
> example:
> 
> http://www.edtp.com/
> 
> Comments? Phil? Anybody? Don't all speak at once... ;) ,
> Matt
>