-----Mensaje original-----
De: Fred [mailto:[EMAIL PROTECTED]]
Enviado el: Friday, May 18, 2001 8:20 PM
Para: Foxboro DCS Mail List
Asunto: Re: NodeBus versus Ethernet
I believe that the only packets that are greater than the 1536 size (with I
think is a standard), that I know of have to do with support of diskless
workstations (WP20 and WP30).
----- Original Message -----
From: James Kahlden <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, May 15, 2001 3:39 PM
Subject: Re: NodeBus versus Ethernet
I recently attended user group meeting where Craig Ouellette of Foxboro TAC
spoke to us about nodebus communications. The following is what Craig had
to say about the nodebus.
"The I/A Nodebus uses redundant cable communications based on the IEEE 802.3
standard. Electrically the polarity is reversed from standard Ethernet.
The characteristic impedance is about 47 ohms instead of 50 ohms. Some of
the diagnostic messages have larger than standard packet lengths, but
otherwise it follows Ethernet rules."
Hope this helps.
Jim Kahlden
[EMAIL PROTECTED]
>>> [EMAIL PROTECTED] 05/15/01 12:30PM >>>
From: Timothy A. Ruhland
My understanding is that Foxboro reversed the "sense" on the Nodebus, i.e.
0s are 1s and 1s are 0s, or something like that (AJ will give us the
straight poop I am sure) to make it so you could not connect a standard
ethernet device to your nodebus. Given that the nodebus evolved in the late
80s, this was a very reasonable thing for them to do (IMHO). After all, can
you imagine the mess if you just used standard out of the box ethernet and
then had customers plugging any old box onto their nodebus?
Corey R Clingo <[EMAIL PROTECTED]> on 05/15/2001 01:40:30 PM
Please respond to "Foxboro DCS Mail List"
<[EMAIL PROTECTED]>
To: Foxboro DCS Mail List <[EMAIL PROTECTED]>
cc: (bcc: Timothy A. Ruhland/506538/EKC)
Subject: Re: NodeBus versus Ethernet
The DNBI/DNBT, among other things, handles the switching between the
redundant
nodebus segments. Your DNBI/DNBT actually connects to the AW/WP via an
ethernet
card (the DNBI also uses a serial port, I presume for the switching and
other
types of data; the DNBT does it all "in-band" over the ethernet
connection).
The packets going out le0/hme0 on the AW/WP, through the DNBI/DNBT, and out
on
the nodebus, probably conform to 802.3.
Actually, 802.3 is an old standard in itself. It is not used any more on
modern
networks, because IIRC, it doesn't allow multiple protocols (e.g., IP and
IPX)
to traverse the wire simultaneously. This is not an issue with the
nodebus,
obviously.
Corey Clingo
Sr. Engineer
BASF Corporation
Hi All,
In all Foxboro documentation, there is a differentiation between Ethernet
and
NodeBus. However, Foxboro states clearly that NodeBus is according to IEEE
802.3
standard. This implies that you can connect AW or WP directly through an
Ethernet card. so, why using DNBI !!!!. the only difference between old
Ethernet
and IEEE 802.3 standard I know is in the "type" field in the frame
structure and
all new Ethernet cards are according to IEEE 802.3 Standard. So, what is
realy
the difference??.
Regards
Ashraf Tantawy
-----------------------------------------------------------------------
This list is neither sponsored nor endorsed by the Foxboro Company. All
postings from this list are the work of list subscribers and no warranty is
made or implied as to the accuracy of any information disseminated through
this medium. By subscribing to this list you agree to hold the list
sponsor(s) blameless for any and all mishaps which might occur due to your
application of information received from this mailing list.
To be removed from this list, send mail to
[EMAIL PROTECTED]
with "unsubscribe foxboro" in the Subject. Or, send any mail to
[EMAIL PROTECTED]
-----------------------------------------------------------------------
This list is neither sponsored nor endorsed by the Foxboro Company. All
postings from this list are the work of list subscribers and no warranty
is made or implied as to the accuracy of any information disseminated
through this medium. By subscribing to this list you agree to hold the
list sponsor(s) blameless for any and all mishaps which might occur due to
your application of information received from this mailing list.
To be removed from this list, send mail to
[EMAIL PROTECTED]
with "unsubscribe foxboro" in the Subject. Or, send any mail to
[EMAIL PROTECTED]
-----------------------------------------------------------------------
This list is neither sponsored nor endorsed by the Foxboro Company. All
postings from this list are the work of list subscribers and no warranty
is made or implied as to the accuracy of any information disseminated
through this medium. By subscribing to this list you agree to hold the
list sponsor(s) blameless for any and all mishaps which might occur due to
your application of information received from this mailing list.
To be removed from this list, send mail to
[EMAIL PROTECTED]
with "unsubscribe foxboro" in the Subject. Or, send any mail to
[EMAIL PROTECTED]
