Thanks, Mike,
This really helps. I am not sure how the RS232 is
wired on the TS-7200 board. I do know the pinout
though. And the RXD and TXD lines for the RS232 are
seprate from the data lines for RS485 on the DB9
connector.
--- Michael L Howard <> wrote:
>
> Hi Art,
>
>
> RS485 is generally not directly supported by the
> uart. The UART can be set to send and receive with
> our without flow control, but the HW flow control
> logic is typically used in RS485 circuits. Do you
> know that the RS232 circuit is supposed to have a
> level converter/driver? That driver is connected
> onto the input/output of the UART between the DB9
> and the UART. For RS485, one of the UART's output
> signals is connected to an enable line of the driver
> (this enable line is not needed for RS232). Uarts
> that have hardware flow control will assert the RTS
> signal when there is a character to send and wait
> for the receiver to assert their CTS signal (which
> is connected to your RTS) before sending. When the
> recieve buffer gets filled up, the receiver will not
> assert CTS even if the RTS is asserted. This is a
> purely hardware function, so you will not have any
> control over this besides just setting it up.
> For RS485, the RTS line from your UARTs trasmit
> logic is often just wired to the line driver enable.
> This means that the RS485 driver is on as long as
> your UART wants to send stuff. If your system works
> like this and you disable HW flow control, then the
> RTS line will either be always on or always off.
> Either nothing gets out or nothing gets in.
> There is a slight chance that a different control
> line runs the driver, but this would require
> software support in the serial driver, so you would
> probably know about that from the card manufacturer
> already.
>
> I think you want the HW flow control on.
>
> Mike
>
> -----Original Message-----
> >From: Art <>
> >Sent: Aug 23, 2006 5:02 PM
> >To:
> >Subject: [ts-7000] Re: rs232 vs rs485
> >
> >Ok,
> >
> >That means that the Com2 may be locked into a
> transmit mode until It
> >gets put into receive?. This makes sence but I do
> not set the
> >transmition state and I thought it would default to
> the RS232
> >functions.
> >
> >--- In Michael L Howard
> <> wrote:
> >>
> >> Hi Art,
> >>
> >> RS422 and RS485 are multi-drop serial buses.
> This means that
> >multiple senders could conceivably be transmitting
> characters at the
> >same time. In practice, the devices take turns
> transmitting, but
> >this requires that each device must be able to shut
> off its' driver
> >circuitry when idle. I believe that it is typical
> to use the RTS
> >output of the handshake circuit to turn the
> transmit driver off and
> >on automatically.
> >>
> >> The RS485 line will have some way to control the
> enable/disable of
> >the driver circuit.
> >>
> >> Mike
> >>
> >>
> >> -----Original Message-----
> >> >From: Art <>
> >> >Sent: Aug 23, 2006 12:47 PM
> >> >To:
> >> >Subject: [ts-7000] Re: rs232 vs rs485
> >> >
> >> >Yan
> >> >
> >> >Thanks for the quick responce. The question I
> was asking was
> >intent
> >> >on getting some information on a com port that
> has the ability to
> >run
> >> >rs485 vs a com port that can just run rs232. I
> have a TS-7200
> >with
> >> >rs485 capable port. I have it setup to run
> rs232. I am running
> >> >rs232 on the other end. I have hardware and
> software flow control
> >> >disabled on both ends. Yet it seems to stop
> sending/receving.
> >But
> >> >what I was asking is for the diffrences in
> hardware on the ts-7200
> >> >for just rs232 vs (rs232 and rs485) on a com
> port. I get the same
> >> >software to run fine on COM1 vs COM2(get's
> stuck).
> >> >
> >> >--- In "Yan Seiner"
> <yan@> wrote:
> >> >>
> >> >> --- In "Art"
> <kingartjr@> 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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