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handshaking with RS-232

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gg

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Excuse me, im just sending data from my device(rs-232 interface circuit) to the computer. Do i have to provide handshaking??? Or i can just use the RD and TD pin on on the serial port???
 

papyaki

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Hi,

You can send to, and receive data from a PC without handshake. But both side must have all handshake options disabled.

Hardware hanshake through RTS/CTS control must be disabled. Software handshake through XON/XOFF must also be disabled.

On your PC, if you are working with hyperterminal, you can easely do that by changing the properties of the serial COM you want to use.

In your post you took about TD and RD pins. Dont forget to connect GND pin between the equipements.
 

marring

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handshake is really important when you transfer with high speed. When use hardware handshake, the hardware will manage your data transfer automatically, you just read data and use it only.

However, handshake helps you do not loss your data. :D
 

waterman

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You could interface with the PC COM port without handshake. Just use TX and RX signals. For my personal experience, I never lose data if the environment is not noisy and the baud rate of both sides (PC and 8051) is set correctly. The highest baud rate I ever used is 115.2 Kbps for receiving and transmitting.

On PC you could use HyperTerminal for receiving data in ASCII form.
Or write your own application program to fit your requirement

Hope this helps
 

Regnum

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gg said:
Do i have to provide handshaking??? Or i can just use the RD and TD pin on on the serial port???

Driving handshake isn't mandatory, but You should use it to avoid overflow risk.
 

Kevin Weddle

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I am conviced the best way to handle communications is to test a line that is already set up. You can be sure of the physical connection and you can record the occurances on each line with an oscilloscope. You can determine who sent the signal by the voltage polarity on the line during a sink or source operation. The voltage level is changing but you can still get an average and the polarity will indicate direction.
 

johnyaya

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I have found that the need for handshaking (hardware or software) usually comes from buffer sizes along with data processing latancy. Without handshaking, buffers can overflow if the data is not processed in time.

If data stream is continuously transmitted at 300 baud you would probably need only a small buffer without buffer overflows. If transmitting continuously at 115.2K you would need much larger buffers.

You can always bypass hardware handshaking later if one device doesn't support it, otherwise you will need to handle the potential buffer overflow situation. Is buffer overflow recovery an acceptable condition (data loss)?

Hardware handshaking can also cause grief when the source device cannot send data due to handshaking. This could cause a transmit buffer overflow.

So, to answer your question, Yes... and No. More details needed to make a good recommendation.
 

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