What possible methods of oversamping can be done between a dte and a
dce? I am aware that if the dte is async (such as it uses a serial
port) and the modem is working synchronously, that the sample rate at
the modem has to be quadruple that of the dte's sampling rate. For
example in hyperterminal i would work with 4800bps and the modem would
be set to work with 19200. Is it possible to oversample when the DTE
works synchronously and so does the DCE? would it at all be necessary?
Right now I have a lab but I can't check this over long distances.
Also, is it possible to oversample if the DTE is synchronous and the
DCE only works asynchronously? if not then what would be the necessary
procedure for these two machines to operate in a basic network, meaning
DTE (sync) -> DCE (async) ~~~ DCE (async) <- DTE (sync)

You guys are the best Merry christmas, hannukah, or any other
holiday that applies.

<kazdan@gmail.com> wrote in message
news:1135611129.517588.37860@g43g2000cwa.googlegro ups.com...
device is running the slower of the two.

There may be some data corruption but if you are using some sort of polling
then data the device that gets the seemingly random garble usually will
request a resend of the poll. I have run circuits at 2x over-sampling but
4x was better. The higher the over-sampling rate the lower the distortion
of the Async data.

They do make async/sync adaptors that can be purchased and what many people
never realized was that many of the better quality "external" modems could
be set to run in a Sync mode, eliminating the need to over-sample or use an
external async/sync adaptor. (Time to check out the modem manual on your
boxes and see if they can be switched to a sync mode.) Many if not most of
the Motorola or VanguardMS modems, have both modes built in but they have to
be configured to do use one or the other, and some can switch from one to
the other by either a AT command or other language depending on what it is
designed/set to handle.

Trying to over clock a sync to sync connection is usually a disaster waiting
to happen. If/when you get it working it will be unstable as the devices
are looking for the data and clock signals to align perfectly.

GlowingBlueMist wrote:
snip

In the case where the DTE is sync, and the DCE async, in the majority of
cases no data will pass at all because the sync DTE will expect Tx and
Rx clocks (pins 15 & 17 of RS232) FROM the DCE , and a "standard" async
DCE does not provide such clocks. Also the async DCE may expect the data
characters to be framed by start and stop bits, which are not used by
the vast majority of sync DTE data protocols.

--reed