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'[EE]: how to check rs232 DTR pin.'
2002\10\03@160051 by andre abelian

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Hi to all,

I have a software it suppose to turn on
Rs232 dtr line on and off I think it
Doesn't work. What I remember on DB9 pin 4
Is DTR but what I do not know is DTR open drain?
Just incase I added 10k pull up resister. I still
Do not see any changes. I already checked RX and TX
On same com port they work fine. My question is how
Can I check RS232 DTR line on and off?
Any help will appreciate.

Andre

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2002\10\03@172736 by Wagner Lipnharski

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andre abelian wrote:
> Hi to all,
>
> I have a software it suppose to turn on
> Rs232 dtr line on and off I think it
> Doesn't work. What I remember on DB9 pin 4
> Is DTR but what I do not know is DTR open drain?
> Just incase I added 10k pull up resister. I still
> Do not see any changes. I already checked RX and TX
> On same com port they work fine. My question is how
> Can I check RS232 DTR line on and off?
> Any help will appreciate.
>
> Andre
>
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What side of the interface is your device?
DTE (equipment) or DCE (modem) ?

If you are trying to control DTR, I understand you should be the DTE
(Equipment), since DTR means "Data Terminal Ready", a circuit that tells
the MODEM that the "terminal" is ready.   If this is true, then your
circuit should drive the DTR via a RS232 chip, or if you can, control DTR
with +8 and -8V (from 6 to 14V is ok), with transistors, proper RS232
drivers or something like that.

DTR or any other RS232 circuit is open drain, all of them are drivers for
positive and negative voltages.

Why don't you explain better your installation, pinouts, circuits, levels,
then probably we could help better.

This is the pinout of the DC9 connector:

DC-9 Connector
-------------------------+------------------------
Pin   Signal             | Pin  Signal
-------------------------+------------------------
1  CD   Carrier Detect   | 6  DSR  Data Set Ready
2  RXD  Receive Data     | 7  RTS  Request to Send
3  TXD  Transmit Data    | 8  CTS  Clear to Send
4  DTR  Data Term. Ready | 9  RI   Ring Indicator
5  GND  Signal GND       |
-------------------------+------------------------

/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
Wagner Lipnharski - UST Research Inc
Orlando FLorida - USA - http://www.ustr.net
/_/_/_/ Atmel AVR Consultant /_/_/_/

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2002\10\03@175525 by Wagner Lipnharski

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Wagner Lipnharski wrote:
[snip] oops, correcting:
>
> DTR or any other RS232 circuit is NOT open drain, all of them are drivers
> for positive and negative voltages.

/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
Wagner Lipnharski - UST Research Inc
Orlando FLorida - USA - http://www.ustr.net
/_/_/_/ Atmel AVR Consultant /_/_/_/

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2002\10\03@182611 by andre abelian

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Wagner,

Thanks for your replay. my device is a pic interface
that needs reset to start. Windows based custom software on pc side
suppose to turn on DTR pin to reset the pic but I do not see
it is doing it. Is there any test software I can use to test
DTR pin?

Andre




What side of the interface is your device?
DTE (equipment) or DCE (modem) ?

If you are trying to control DTR, I understand you should be the DTE
(Equipment), since DTR means "Data Terminal Ready", a circuit that tells
the MODEM that the "terminal" is ready.   If this is true, then your
circuit should drive the DTR via a RS232 chip, or if you can, control
DTR
with +8 and -8V (from 6 to 14V is ok), with transistors, proper RS232
drivers or something like that.

DTR or any other RS232 circuit is open drain, all of them are drivers
for
positive and negative voltages.

Why don't you explain better your installation, pinouts, circuits,
levels,
then probably we could help better.

This is the pinout of the DC9 connector:

DC-9 Connector
-------------------------+------------------------
Pin   Signal             | Pin  Signal
-------------------------+------------------------
1  CD   Carrier Detect   | 6  DSR  Data Set Ready
2  RXD  Receive Data     | 7  RTS  Request to Send
3  TXD  Transmit Data    | 8  CTS  Clear to Send
4  DTR  Data Term. Ready | 9  RI   Ring Indicator
5  GND  Signal GND       |
-------------------------+------------------------

/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
Wagner Lipnharski - UST Research Inc
Orlando FLorida - USA - http://www.ustr.net
/_/_/_/ Atmel AVR Consultant /_/_/_/

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2002\10\03@185726 by Tony Nixon

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Hi Andre,

I just whipped up a little exe program that can toggle the DTR pin.

http://www.bubblesoftonline.com/projects/dtr.zip

andre abelian wrote:
>
> Wagner,
>
> Thanks for your replay. my device is a pic interface
> that needs reset to start. Windows based custom software on pc side
> suppose to turn on DTR pin to reset the pic but I do not see
> it is doing it. Is there any test software I can use to test
> DTR pin?

--
Best regards

Tony

mICros
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@spam@salesKILLspamspambubblesoftonline.com

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2002\10\03@191629 by Tom Messenger

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Why the piclist is *the* place for information...


At 08:54 AM 10/4/02 +1000, you wrote:
{Quote hidden}

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2002\10\03@193727 by Bill Westfield

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You're desparately in need of an rs232 "breakout box" that shows the state
of appropriat signals on some LEDs.  There's a ridiculously expensive one
here: http://www.bb-elec.com/product.asp?sku=9PMTT&dept_id=136 (DB25 versions
are generic and sell for less than $10, but I couldn't find any cheap DB9
versions in quick web search.  Grr.)  Given the ... randomness... of rs232
cables, something like this is a near-necessity.  In addition to checking
for expected signal transitions, you can use it to make sure that your
connection is DCE on one side and DTE on the other side :-)

BillW

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2002\10\03@194619 by andre abelian

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Tony,

Thank you very much for you quick test program.
I also like to appreciate Wagner's replay too.
You guys are the best.

Andre





Hi Andre,

I just whipped up a little exe program that can toggle the DTR pin.

http://www.bubblesoftonline.com/projects/dtr.zip

andre abelian wrote:
>
> Wagner,
>
> Thanks for your replay. my device is a pic interface
> that needs reset to start. Windows based custom software on pc side
> suppose to turn on DTR pin to reset the pic but I do not see
> it is doing it. Is there any test software I can use to test
> DTR pin?

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
TakeThisOuTsalesEraseMEspamspam_OUTbubblesoftonline.com

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2002\10\03@233911 by Brent Brown

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Get this terminal program from here, it's the best!

http://bray.velenje.cx/avr/terminal

I've been using it for about a couple of months now and it has some
pretty handy features specially for hardware/software developers.
Allows you to manually toggle DTR and RTS so should help you.

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Mobile/txt: 025 334 069
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2002\10\04@080359 by Olin Lathrop

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> Is DTR but what I do not know is DTR open drain?

All RS-232 signals are actively driven in both directions.


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2002\10\04@194322 by Ray Gallant

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source=If your just looking for visual check of DTR or any other pins on that connection, consider the following 3 component simple circuit.  A signal diode, a 3ma current regulator such as a J509 plus one LED.

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