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Whats the Difference between Readline and readexisting

Posted on 2011-09-02
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Last Modified: 2012-08-13
I have setup a com port read property and trying to send a signal from my external device to my PC. When I use the com port readline I cannot see anything over the com port, however when I use the readexisting I can see the data over the com port. Whats the difference?
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Question by:cmdolcet
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Jacques Bourgeois (James Burger) earned 252 total points
ID: 36476850
ReadExisting gets any data that is lying in the receive buffer.

ReadLine waits until it detects an end of line value in the data. If data has been received but there was no end of line code in the data, Readline returns nothing. This makes it easier to read text line by line, because the system takes care of identifying the end of each line.

If the type of data you receive is not made of  text, ReadLine is useless. It might never trigger, because the com port might never receive end of line values. And if it does (usually values 13 and/or 10), they won't really represent and and of line, they are probably only those values in binary data.
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by:cmdolcet
ID: 36477889
I know my data end of line is a CR would this be the same?
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by:Fernando Soto
Fernando Soto earned 248 total points
ID: 36477947
Hi cmdolcet;

The SerialPort.ReadLine Method expects to see a NewLine to mark the end of the string. The new line is a sequence of two characters, \r\n, which represents a Cr and Lf NOT just a CR and is the reason why you are not seeing any response on the line.

Fernando
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