Re: RS-232, No short No send?

From: boki (bokiteam_at_ms21.hinet.net)
Date: 10/07/04 

Date: 6 Oct 2004 18:09:19 -0700

"Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message news:<dgV8d.591$K95.102@newsfe2-gui.ntli.net>...
> "Boki" <bokiteam@ms21.hinet.net> wrote in message
> news:ck14g8$bfl$1@netnews.hinet.net...
> > Deaer Roger,
> > Yes, I connected pin.3(TXD) to oscilloscope signal
> and
> > pin.1 connected to oscilloscope ground.(didn't swap lines)
> > but there is no signal in oscilloscope. If I short pin.2 pin3, it works.
> >
> > I am confusing why it didn't send out signals when pin.2 pin.3 are not
> > short. ( I floting all other pins.,.except signal and ground.)
> >
> > Best regards,
> > Boki.
> OK.
> One thought, is that if the receive input is disconnected, the code will
> be seing a continuous 'break'. It may be that this is disabling the
> transmission. Try just pulling the RX line low, and then seeing if TX
> starts. The handshake lines should have a suitable signal available (RTS
> or CTS).
>
> Best Wishes

    Sorry, there is no 'break' can be detected by my program, because
I floating all other pins, I only connect TX, RX, Ground, to scope.

    I check it works or not by its TX and RX pins. If I short
pin.2(TX) and pin.3(RX) then I can see the RX signal received the
signal I send from TX( or say, there is a signal send out from TX), if
I open TX and RX, the TX is no output signal anymore....@@ (program is
still sending signal)

Best regards,
Boki.

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