| Author |
Message |
Guest
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 Posted:
Mon Sep 26, 2005 2:51 pm Post subject:
RTS problem |
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Hi all, and thanks for reading.
While working with modems, i've stated a strange thing on flow control.
I've connected 2 computer with 2 modems connected each other (not via
phone line, but directly). Flow control is enabled for both terminal
using the "AT&K3" command).
This is the communication scheme :
TX PC1 : "ATD<CR>" (initiating call)
TX PC2 : "ATA<CR>" (answer)
TX PC1 : "<CR><LF>CONNECT 19200<CR><LF>" (PC1 connected)
TX PC2 : "<CR><LF>CONNECT 19200<CR><LF>" (PC2 connected)
[starting communication]
TX PC1 : "Hello world" (sending)
RX PC2 : "Hello world" (receiving)
[clearing the RTS line on PC2]
TX PC1 : "AZERTY" (sending)
RX PC2 : (...) (nothings append)
TX PC2 : "QWERTY" (sending)
RX PC1 : "QWERTY" (receiving)
Up to this point, all is normal. By clearing the RTS line, the modem
stop sending characters to PC2.
Normally, setting the RTS line will (re)allow reception :
[setting the RTS line]
TX PC1: "AZERTYUIOP" (sending)
RX PC2: (...) (nothings append !!!)
It seems that the modem does't see that the RTS line is in the 'ready
to receive' state !
To be sure that is not an hardware problem, i've tested the following :
TX PC2 : "+++" (escape sequence)
RX PC1 : "+++"
RX PC2 : "<CR><LF>OK<CR><LF>" (back to command mode!)
Since the modem respond to the escape sequence, it's not an hardware
problem.
Getting back to "connected mode" :
TX PC2 : "ATO" (back to 'connected mode')
RX PC2 : "<CR><LF>CONNECT 19200<CR><LF>"
TX PC1 : "AZERTY" (sending)
RX PC2 : (...) (nothing received)
The modem still ignore the RTS line. What appends ? I absolutely need
flow control, since the modem is intended to be embedded in a
microcontroller system with very small RX buffer.
Any comments ? |
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Guest
|
| Posted:
Mon Sep 26, 2005 4:20 pm Post subject:
Re: RTS problem |
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It seems that was a firmware bug (Olitec speed'com v92 ready). By
updating the firmware, the problem disapear. |
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Jamil
Guest
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| Posted:
Mon Oct 17, 2005 1:35 am Post subject:
Re: RTS problem |
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how is external modem is interfaced with microcontroller ?
can u write a source code for this , plz i need a code
i m not expert in programming
nono240@gmail.com wrote:
| Quote: | Hi all, and thanks for reading.
While working with modems, i've stated a strange thing on flow control.
I've connected 2 computer with 2 modems connected each other (not via
phone line, but directly). Flow control is enabled for both terminal
using the "AT&K3" command).
This is the communication scheme :
TX PC1 : "ATD<CR>" (initiating call)
TX PC2 : "ATA<CR>" (answer)
TX PC1 : "<CR><LF>CONNECT 19200<CR><LF>" (PC1 connected)
TX PC2 : "<CR><LF>CONNECT 19200<CR><LF>" (PC2 connected)
[starting communication]
TX PC1 : "Hello world" (sending)
RX PC2 : "Hello world" (receiving)
[clearing the RTS line on PC2]
TX PC1 : "AZERTY" (sending)
RX PC2 : (...) (nothings append)
TX PC2 : "QWERTY" (sending)
RX PC1 : "QWERTY" (receiving)
Up to this point, all is normal. By clearing the RTS line, the modem
stop sending characters to PC2.
Normally, setting the RTS line will (re)allow reception :
[setting the RTS line]
TX PC1: "AZERTYUIOP" (sending)
RX PC2: (...) (nothings append !!!)
It seems that the modem does't see that the RTS line is in the 'ready
to receive' state !
To be sure that is not an hardware problem, i've tested the following :
TX PC2 : "+++" (escape sequence)
RX PC1 : "+++"
RX PC2 : "<CR><LF>OK<CR><LF>" (back to command mode!)
Since the modem respond to the escape sequence, it's not an hardware
problem.
Getting back to "connected mode" :
TX PC2 : "ATO" (back to 'connected mode')
RX PC2 : "<CR><LF>CONNECT 19200<CR><LF>"
TX PC1 : "AZERTY" (sending)
RX PC2 : (...) (nothing received)
The modem still ignore the RTS line. What appends ? I absolutely need
flow control, since the modem is intended to be embedded in a
microcontroller system with very small RX buffer.
Any comments ? |
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