--- In "Art" <> wrote:
>
> Is there any diffrences in a rs485 configured port that would prevent
> it from functioning as a standard rs232 port? I then ask what are the
> diffrences? it seems event when I turn the flow control off on this
> port it still functions as if it were in place. Getty doesn't seem to
> work well on com2.
>
rs232c and rs485 specify different electrical standards. I am not
sure what you are asking.
Typically rs485 is run on 2 or 4 wires, with no flow control lines.
I'm not that familiar with the 4 wire setup; I've only used
half-duplex (2 wire). Each station turns its transmitter on when it
wants to say something; the other stations are supposed to respect
that and not transmit.
RS232c is point-to-point, and provides for all sorts of redundancy
(the full spec has secondary RX and TX lines, even...) There are
liens that each station is supposed to turn on and off when it is
ready. There are also signal lines for special events like carrier
detect.
Basically, RS232c was designed to talk short distances to a modem, an
RS485 was designed to talk long distances to multiple peers. Also,
an RS485 bus is (I believe) a voltage differential setup, whereas
RS232 is referenced to 0, but I could be getting confused with another
bus I am working with...
So when you switch a port from rs232 to rs485, you lose all hardware
flow control, since there is none.
--Yan
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