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???
06/09/04 08:54
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#72154 - RE: Problem with Comm Port
Responding to: ???'s previous message
Ahmed Barakat said:
I was makin a burnner using serial communication through Comm port,

In what way are you using the Comm port?
Are you using it purely for data communication (which is its sole design purpose), or are you also trying to draw power from it?

Although it can be done, using an RS232 port as a power source is at best a bodge (kludge) - they were never designed for this purpose!

Are you using a properly-designed, standards-compliant, RS232 transceiver circuit, or just a quick bodge with a couple of transistors?

Ahmed Barakat said:
when i use the S/W that communicate with port a small change in the voltage level is detected on the port

What Voltage?
Where are you measuring this?
How are you measuring it?

Please post a schematic.

Ahmed Barakat said:
program written in C++ that write direct to the port and it works perfect but cause a large difference in the port voltage level when i write a cgaracter on the Keyboard, i've tried to use Hyper Terminal but when i began writting on keyboard nothing occured for the signal level

Are you sure that you have exactly the same setting in both your C++ and Hypoterminal; ie:
* Baud rate;
* Number of Data bits;
* Number of Stop bits;
* Parity;
* Flow Control.

Also note that Hypoterminal has other options, like adding a Linefeed whenever you type a Carriage-Return.

Of course, when your C++ sends data, the characters will come in very quick succession, but when you type by hand on a keyboard there will be a much longer delay between them!

List of 6 messages in thread
TopicAuthorDate
Problem with Comm Port            01/01/70 00:00      
   RE: Problem with Comm Port            01/01/70 00:00      
   RE: Problem with Comm Port            01/01/70 00:00      
      RE: Problem with Comm Port            01/01/70 00:00      
         Multimeter measurement is meaningless            01/01/70 00:00      
         Troubles with Hypoterminal            01/01/70 00:00      

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