RE: Loop connection

Thanks Allen

I'm Soory for bad my explain.
My thinking network is following.
Ring wireing on Sw box+node4
if Sw is turn off, (a) to (b) short wire is shut down.
(a) to (b) => (a) to (d) to (c) to (b)
if Sw is turn on , (a) to (b) short wire is conect.
Sw control is node4.
Each node conect branch from Ring wireing.
Terminator is include 2nodes.

If node4 turn on SW, CAN bus is Loop toporogy.
CAN bus is not defined Loop toporogy.
Why not?

Image of connection.
(d) ====================(a)
||  Ring Wireing                        || (SW box+node4)
(c)====================(b)
    ||                   ||               ||
node1           node2        node3…

Best Regards,
Hideki MASUDAYA

From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Allen Pothoof
Sent: Tuesday, March 31, 2015 10:46 PM
To: [email protected]<mailto:[email protected]>
Subject: RE: [CANLIST] Loop connection


Are you talking about a ring topology: node 1 connected to node 2, node 2 to node 3, node 3 to node 4 and node 4 back to node 1?

CAN is designed as a bus topology, where a node broadcasts it's information onto a common backbone and other nodes can consume or ignore it, depending on their needs.

In a ring topology, every node has to handle each packet that comes in and forward it on to the next node.

If you took a CAN bus and "connected the ends together", what I suspect would happen is that the nodes would go bus off fairly quickly due to bus errors.  I'm not sure what kind of reflectance you'd get as the message tried to "go both ways around the ring" and I don't know where you'd put the terminating resisters (or if it even makes sense to talk about "terminating" resisters).

In short, CAN is not designed to work in a ring topology.

Al.
________________________________
From: [email protected]<mailto:[email protected]>
To: [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Subject: RE: [CANLIST] Loop connection
Date: Mon, 30 Mar 2015 23:57:04 +0000
Thanks  Allen，

I am sorry for Mail title.
I forgot changing title.

I want to know pysical reason.
If I make Loop conectiion of CAN network,the system is not conection?
Or  comunication is still alive?

I think sytem node is about 4~8units.

Kind Regurds,

hideki MASUDAYA



From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Allen Pothoof
Sent: Tuesday, March 31, 2015 6:07 AM
To: [email protected]<mailto:[email protected]>
Subject: RE: [CANLIST] Loop connection


 Hideki,

First of all, I've changed the subject title; it's not considered polite to hijack other people's threads.

To your question as to why CAN "is not Specify Loop Type connection", bear in mind that CAN is a broadcast network, not a point-to-point network.  As such, it is somewhat akin to a radio: a node "broadcasts" it's data but doesn't know how many other nodes are listening; it may be 1 or it could be 100.  If some number of those nodes go off-line or become disconnected, the broadcasting node neither knows nor cares.  The only requirement is that there must be at least 1 other node active to acknowledge the transmission.

Regards,
Al Pothoof
________________________________
From: [email protected]<mailto:[email protected]>
To: [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Subject: RE: [CANLIST] Busmaster CAN bus simulator -- "Function editor"
Date: Mon, 30 Mar 2015 08:44:10 +0000
Hello

I have a question  about CAN Netowork.
CAN Network is not Specify Loop Type connection.

I want to know why .
I  consider Redundant system of CAN Network.
If the system detect cutting CAN wire, the system connect another CAN wire.

Its system problem is ability of loop connection.

Kind Regurds,

hideki MASUDAYA