what a daisy chain is?

[jasonleehan@gmail.com]

Hi everyone,
It seems a simple question.But I still have something i
cannot completly understand.

A daisy chain is often used a mulidrop topology, which need an
end-termination. And, source-termination doesnot work properly in
daisy chain,because the device in the middle of the chain would get a
plateau.
So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?


---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|


thank you all!

 

[Spurious Response]

Hi everyone,
It seems a simple question.But I still have something i
cannot completly understand.

A daisy chain is often used a mulidrop topology, which need an
end-termination. And, source-termination doesnot work properly in
daisy chain,because the device in the middle of the chain would get a
plateau.
So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?


---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|


thank you all!

It's a repeater, so up to the point at which the signal level falls
below a specific point.



In digital it would be called bit-error-rate.

 

[Noway2]

Hi everyone,
It seems a simple question.But I still have something i
cannot completly understand.

A daisy chain is often used a mulidrop topology, which need an
end-termination. And, source-termination doesnot work properly in
daisy chain,because the device in the middle of the chain would get a
plateau.
So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?


---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|


thank you all!

The problem lies in how source termination works. By setting the source
(termination) resistor equal to the impedance of the line, it causes a
wave to be launched on to the line that is at 50% amplitude. When the
signal hits the (single) receiver which is approximately an open circuit
the amplitude doubles, hence appearing as normal at the receiver end.
The signal than travels back (reflected - again at 50% amplitude)
towards the source where it is squelched by the termination resistor.

The receiver sees the full amplitude because of the interference caused
by the original signal and its reflection. Any devices in the middle of
the chain would see a 50% waveform, twice.

The purpose in load end termination in the daisy chain is to allow all
devices in the chain to see the full amplitude signal - once and to
prevent reflections on the line which will interfere with transmission.

 

[whit3rd]

A daisy chain is often used a mulidrop topology, which need an
end-termination.

There are two kinds of daisy-chain: one (like SCSI or thinwire 10base2
Ethernet) supports multiple attachment to a backbone, which
is terminated at each of two ends. The other is based on
repeaters (Firewire uses these) so all links are terminated
at each end, but repeaters make another port available to continue
the chain.

So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?

---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|

This isn't clear to me. In the case of SCSI, there was a 'stub'
allowed
of four inches, so a very short (4 inch) bus could operate with only
one terminator. In the case of 10base2 Ethernet, that WASN'T allowed,
because the terminators determined some signal levels that
had to be predictable in order to detect collisions.

In neither case is 'source termination' a recognizable feature; all
the devices on the chain can be sources, and it's the
CHAIN that has terminations.

 

[neon]

a daisy chain is referal to a connection that goes from point A to a point of infinity connected SERIALY continiously. an example of a daisy chain would be a ground connection from a source connecting all cmponents serialy that is a daisy chain as opposed to every conponet ground returning to the source or point A.

 

[Rich Grise]

Hi everyone,
It seems a simple question.But I still have something i
cannot completly understand.

A daisy chain is often used a mulidrop topology, which need an
end-termination. And, source-termination doesnot work properly in
daisy chain,because the device in the middle of the chain would get a
plateau.
So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?

---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|

That's not a daisy chain - that's a multi-drop. A daisy chain looks like
this:
-------- --------------------- -------------
Driver_0-------revceiver_1--Driver_1-------receiver_2--etc.
-------- --------------------- -------------
where each item has an input and output, and the connection goes from
one's output to the other's input, and so on.

As far as multi-drop, you have to look at driver capacity and timing and
stuff like that.

Hope This Helps!
Rich

 

[joseph2k]

Hi everyone,
It seems a simple question.But I still have something i
cannot completly understand.

A daisy chain is often used a mulidrop topology, which need an
end-termination. And, source-termination doesnot work properly in
daisy chain,because the device in the middle of the chain would get a
plateau.
So, in a design , i should figure out minimul distance between,
say two receivers. in other words, beyond what distance between two
receivers , source-termination should not be used, and this topology
can be named a daisy chain?


---- ------ -------
Driver---------revceiver_1-----------------------receiver_2
---- ------- --------
|-------------distance---------|


thank you all!

Gods, what a blazing idiot / asshole. Did you read far enough down the hit
list to find wikipedia? It was above this NG wasn't it? Wasn't it
informative enough?