Please anybody can give me a brief idea that using oscilloscope how i
can capture the waveform on a serial link, tranmitting the ASCII letter
'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?

I have connected oscilloscope with serial interface then? then selected
the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
wt to do?

waiting for ur reply?

regards

RsK wrote:
> Please anybody can give me a brief idea that using oscilloscope how i
> can capture the waveform on a serial link, tranmitting the ASCII letter
> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
> 
> I have connected oscilloscope with serial interface then? then selected
> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
> wt to do?
> 
> waiting for ur reply?

You need a terminal emulator program to capture the 
character stream into a file (that you name).  Depending on 
what file format you set the scope to use to format the 
image, you use an image viewer to look at the resulting 
file.  The details are dependent on the scope model and the 
terminal emulator program you have.

John Popelish wrote:
> RsK wrote:
>> Please anybody can give me a brief idea that using oscilloscope how i
>> can capture the waveform on a serial link, tranmitting the ASCII letter
>> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>>
>> I have connected oscilloscope with serial interface then? then selected
>> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
>> wt to do?
>>
>> waiting for ur reply?
> 
> You need a terminal emulator program to capture the character stream 
> into a file (that you name).  Depending on what file format you set the 
> scope to use to format the image, you use an image viewer to look at the 
> resulting file.  The details are dependent on the scope model and the 
> terminal emulator program you have.

Does the OP want to see the letter, or the waveform? The ASCII letter R 
in hexadecimal is 52. RS-232 standard levels are +/- 12 volts, with 
"mark" = +12 and "space" = -12. The line protocol is "mark idle", which 
means that a quiet line is +12. ASCII characters begin with a start bit 
(space), followed by 7 or 8 or 9 data bits (including parity if any), 
and one, 1.5, or two stop bits. The usual is 8 data bits and one stop 
bit. Hex 52 = 0101 0010, which in RS-232 becomes +-+-++-+. When framed 
with start and stop bits, the sequence becomes -+-+-++-++. I generally 
use letter U (hex 55) for testing. It's sequence is -+-+-+-+-+.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

On a sunny day (18 Nov 2006 07:26:52 -0800) it happened "RsK"
<r...@gmail.com> wrote in
<1...@e3g2000cwe.googlegroups.com>:

>Please anybody can give me a brief idea that using oscilloscope how i
>can capture the waveform on a serial link, tranmitting the ASCII letter
>'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>
>I have connected oscilloscope with serial interface then? then selected
>the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
>wt to do?
>
>waiting for ur reply?

OK

>regards

really

As was pointed out you need some terminal program to send the 'R' repeatedly.

When you connect the scope to the serial out RS232 line, the following applies:

1200 Baud is 1200 bits / second, so the time for one bit is about 830 uS.

If you have the terminal program and press 'R' with short intervals, and
trigger the scope on the start bit (pos or negative depends on where you
measure), and set the trace so one division is exactly 1/1200 sec (830us),
then you should be able to see a full character plus start and parity bit
(10 bits in your case = 10 divisions), on the scope.

Works both with a normal and with a storage scope, analog or digital.
If the picture is faint (dim) use auto-repeat..... stick a match in the 'R' key
to hold it down.

Now what you will see is one start bit, the ASCII code for 'R', and a parity bit.
the ASCII code for 'R' is 52 hex, or in binary, with MSB first:
0101 0010

The start bit added
0 0 1 0 1 0 0 1 0 

Parity added (you do not say odd or even):
0 0 1 0 1 0 0 1 0 x

The stop bit added:
0 0 1 0 1 0 0 1 0 x 1

^
scope trigger point
This is what the scope will display.
On the scope you will not see the last '1' if 10 divisions and 1 bit per division, no problem,
that bit is always the same.

In article <1...@e3g2000cwe.googlegroups.com>, 
r...@gmail.com says...
> Please anybody can give me a brief idea that using oscilloscope how i
> can capture the waveform on a serial link, tranmitting the ASCII letter
> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
> 
> I have connected oscilloscope with serial interface then? then selected
> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
> wt to do?

  - Connect CH1 to TXD
  - Select CH1
  - Select CH1 as the trigger source
  - Select trigger slope = negative
  - Vertical amplifier = 1 to 5V/div, depending on the situation
  - Time base = 1msec/div

You should see the initial positive to negative transition with the 
signal low for the start bit.  The rest of the bits should follow 
at 833usec (a little less than a division) intervals. The ten bits 
should almost fill up the display (8.3 divisions).  If the 
characters are being sent one after another the display may be a 
bit unstable.  Depending on the scope, playing with the trigger 
holdoff may help.

-- 
  Keith

RsK wrote:
> Please anybody can give me a brief idea that using oscilloscope how i
> can capture the waveform on a serial link, tranmitting the ASCII letter
> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>
> I have connected oscilloscope with serial interface then? then selected
> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
> wt to do?
>
> waiting for ur reply?
>
> regards

Hi, RsK.  You might want to consider using a "U" (0x55), because each
bit changes (01010101).

Set your timing so you send the character every 50ms. or so, then put
your scope on RxD and set your scope for auto trigger, 5V/div, 5ms/div.
 Tweak your PGT trigger level to +3V, and you should be good to go

Are you having trouble setting the scope, your terminal program
settings, or what?

Cheers
Chris

John Popelish wrote:
> RsK wrote:
> 
>> Please anybody can give me a brief idea that using oscilloscope how i
>> can capture the waveform on a serial link, tranmitting the ASCII letter
>> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>>
>> I have connected oscilloscope with serial interface then? then selected
>> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
>> wt to do?
>>
>> waiting for ur reply?
> 
> 
<piggyback> Sorry, didn't get the OP.
http://www.picotech.com/experiments/serial_data/results.html


A letter R in ASCII is 01010010 in binary. (8 bit - leave off the 
leading zero for 7 bit)

Reversing that to put the least significant bit first, this is 01001010 
- this is the order in which the bits will be sent down the line.

At 1200 Baud, there will be a maximum of 1200 transitions in voltage 
level a second.

Initially, the scope will show a steady input of -12v.

The first transition will be the beginning of the start bit, which will 
take the input to +12v.

~0.8mSec later the least significant bit of the character is sent, as 
this is a 0, the input will go to -12v.

~0.8mSec later, the next least significant bit will be sent - this time 
a 1, so the input will rise to +12v.

The other bits will then be sent, at the same spacing. The parity bit, 
assuming even parity, will be sent as a 1. Then the end bit will be sent 
-this is just a period at -12v to ensure that the next start bit can be 
recognised.


-- 
Sue

Jerry Avins wrote:
> John Popelish wrote:
>> RsK wrote:
>>> Please anybody can give me a brief idea that using oscilloscope how i
>>> can capture the waveform on a serial link, tranmitting the ASCII letter
>>> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>>>
>>> I have connected oscilloscope with serial interface then? then selected
>>> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
>>> wt to do?
>>>
>>> waiting for ur reply?
>>
>> You need a terminal emulator program to capture the character stream 
>> into a file (that you name).  Depending on what file format you set 
>> the scope to use to format the image, you use an image viewer to look 
>> at the resulting file.  The details are dependent on the scope model 
>> and the terminal emulator program you have.
> 
> Does the OP want to see the letter, or the waveform? The ASCII letter R 
> in hexadecimal is 52. RS-232 standard levels are +/- 12 volts, with 
> "mark" = +12 and "space" = -12. The line protocol is "mark idle", which 
> means that a quiet line is +12. ASCII characters begin with a start bit 
> (space), followed by 7 or 8 or 9 data bits (including parity if any), 
> and one, 1.5, or two stop bits. The usual is 8 data bits and one stop 
> bit. Hex 52 = 0101 0010, which in RS-232 becomes +-+-++-+. When framed 
> with start and stop bits, the sequence becomes -+-+-++-++. I generally 
> use letter U (hex 55) for testing. It's sequence is -+-+-+-+-+.
> 
> Jerry

Minor correction; a marking line is -3 <> -15V (logical 1) :)

Cheers

PeteS

PeteS wrote:

   ...

> Minor correction; a marking line is -3 <> -15V (logical 1) :)

Of course. Sometimes my head gets stuffed with current loop facts.

Thanks.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

PeteS wrote:
> RsK wrote:
>> Please anybody can give me a brief idea that using oscilloscope how i
>> can capture the waveform on a serial link, tranmitting the ASCII letter
>> 'R'  with 1 start bit, 1 end bit, 1 parity, with 1200 Baud.?
>>
>> I have connected oscilloscope with serial interface then? then selected
>> the CH1 & CH2 then changed some setting on oscilloscope for RS232 , the
>> wt to do?
>>
>> waiting for ur reply?
>>
>> regards
>>
> 
> To assist in your reading the replies here, I posted a PDF of a 
> simulated scope trace of the letter 'R' (assuming it to be the only 
> transmission) on RS232.
> 
> Cheers
> 
> PeteS

Helps if I identify where, of course

On a.b.s.e.

Cheers

PeteS