[PATCH] Documentation about RS485 serial communications

[Matt Schulte]

On Tue, Nov 16, 2010 at 10:28 AM, Grant Edwards
<grant.b.edwards at gmail.com> wrote:
> On 2010-11-16, Matt Schulte <matts at commtech-fastcom.com> wrote:
>> On Tue, Nov 16, 2010 at 8:30 AM, Pavel Machek <pavel at ucw.cz> wrote:
>>> Hi!
>>>
>>>> Documentation about RS485 serial communications
>>>
>>> I have seen hardware (kontron pmc-6l) that was capable of switching
>>> between RS232, RS485 and one other standard by software.
>>>
>>> Is such hw common? If so, should we have standard interface?
>>
>> In my opinion this type of card is not that common.  Generally
>> speaking the achievable baud rates for this type of multi-protocol
>> card are very limited because of limitations of the transceiver chips.
>
> I'm curious which selectable interface cards you're talking about that
> are slow?  The ones I'm familiar with generally support baud rates up
> to either 460K bps or 921K bps
>
>> It seems that most of the time people would rather have a faster
>> serial port than one that does several different voltages.
>
> Where did you find a selectable interface serial card that couldn't
> support high baud rates?

In my world 460kbps for an RS422 card is slow.  RS422 cards generally
push multi megabit/s rates.

Matt Schulte