UART and RS 232

[Manuv16589]

Hi people,
why Uart devices are connected to rs232 devices even though both are asynchronous standards?

 

[Ian Rogers]

Uart is hardware... RS232 is a software protocol used on that hardware...

 

[simonbramble]

hmmm. Not really. RS 232 is the physical layer standard (that defines the slew rate, voltage level, input impedance of the receiver and driving capabilities of the transmitter). The UART frames the data. Traditionally RS 232 is used with a start bit, stop bit and 8 data bits, inverted logic, but this is not defined in the rs232 standard. However most UARTs driving RS 232 use this standard, so it has become accepted as such

 

[3v0]

Hi people,
why Uart devices are connected to rs232 devices even though both are asynchronous standards?

You can connect UART to UART without the RS232 level shifters. Using the RS232 level shifters extends the distance you can communicate.

 

[Ian Rogers]

Its a touchy subject... but asynchronous transmission... rs485 , rs232 etc.. doesn't necessarily have to be implemented in that way..
I use RS232 protocol WITH a current source / sink to travel over 100 metres on cranes...That is only the software portion.. the hardware I make myself.

 

[3v0]

If you are using a current loop it is not RS232. Or maybe I am understanding.

 

[Ian Rogers]

Its not really anything..... RS232 seems to be the best protocol... so I created a 6mA current loop for the transfer.... 5v connection
Its my hy-brid but the protocol is definitely RS232

 

[Nigel Goodwin]

Its not really anything..... RS232 seems to be the best protocol... so I created a 6mA current loop for the transfer.... 5v connection
Its my hy-brid but the protocol is definitely RS232

As others have said, RS232 is the actually physical connection, with it's +/-12V swing - the protocol you're using is just standard serial, something like 9600N1 (depending exactly what you're using).

Why did you specifically use a current connection?, it's fairly obscure (and only of use in certain circumstances).

 

[Ian Rogers]

the connection is a two wire galvanized steel core with a copper braid outer core... current loop is the best way...

But!!!! enough about my system... I don't want to hi-jack this thread.

 

[3v0]

Manuv16589's question has been well answered.

 

[Ian Rogers]

Nigel... I have always seen RS323 as a protocol.... protocol is language communication.. I saw the hardware... -12/12 volt level shifting as an aide for this protocol.

I may have misunderstood


Hang on.... thinking about it... why else would the chip be an RS232 converter...

 

[Nigel Goodwin]

nigel... I have always seen rs323 as a protocol.... Protocol is language communication.. I saw the hardware... -12/12 volt level shifting as an aide for this protocol.

I may have misunderstood


hang on.... Thinking about it... Why else would the chip be an rs232 converter...

exactly!! :d