Write on pin DTR and read on DSR

[ramses64]

So the only way to do a "dongle" in order to securise my soft is to send a variation of 1and0 on one pin and to receive it on the other ?
There are no pin in order to do what i would like ?
Thanks a lot.

[Dennis_Knutson]

No, there are no pins on RS-232 with a variable output voltage.

[Henrik_Volkers]

Of course the RS232 pins have a variable output voltage:  Since more than less manufactors of hardware ignore the RS232 standard, the output of the pins vary from device to device 😉  some notebooks just have a 5V swing , bad if you want to power a optoisolator with the port 😞  

However, if the org poster want to establish a crude way to communicate, he can use one or two additional IO Pins (RTS,CTS) for a clock signal and do something like a slow  I2C in software.  Since the RS232 is a legacy port, I recomment to add a FTDI USB/serial chip to the pic and use a USB port.  

[ramses64]

Hi,

thanks for your message. Could you help me ? My problem is simple : i want to send a number on a pin (for exemple on DTR), and receive it on one other (for exemple the DSR). So is it possible ? Could you give me an exemple  ? On previously conversation is one vi I have made, and with this, i just can send 1 or 0.
Best regards,

[Dennis_Knutson]

You don't get Henrik's joke (see the ). The voltage output can be different between different UARTs. One implementation may use +/-15. another may use +/-5. IT DOES NOT MEAN YOU CAN VARY THE VOLTAGE LEVEL ON THE SPECIFIC UART YOU HAVE ON YOUR PC. It really does not need to be repeated again. Have you heard of google? Do a google search of rs-232 if you don't believe what I have told you several times.

[Henrik_Volkers]

Are the tools to program a PIC nowadays that simple, that it could be done without deeper knowledge of serial communication protocols...

OK again , you can make a I2C/SPI like communication over the serial port without using TDX /RDX  by bit banging the control lines...

DIG the web and this forum (searchwords: SPI I2C serial ) and you can find stuff like

http://forums.ni.com/ni/board/message?board.id=170&message.id=67409&query.id=279241#M67409

(Hey, did I saw a posting of BEN in there ??)

and

http://forums.ni.com/ni/board/message?board.id=170&message.id=137823&query.id=279456#M137823

now, put it together, mix it, add a spoon full brain and you have your solution

*** OT: What is vacuum ? Damm, I knew it's in my head ...  ****