Real Time Graphing from Com Port Data

[jonathangt923]

when i send 300(decimal) in two bytes 0x01 and 0x2C attached is what is plotted. I'm not sure why it is 10 (decimal) sometimes, and why it is not a pattern 0x01 0x2C 0X01 0X2C... (1 44 1 44 1.... decimal).  I played with the read count, figured it should be 2 but it really didn't make much of a differenec what the read count was

[crossrulz]

That 10 is from your termination character.  You really should not be using the termination character since you are sending binary (hex) data.  Termination characters are only really good for ASCII data.

[jonathangt923]

Took out the termination character, so now i just send high byte then low byte.  attached is how it is graphing now.  Why is it graphing one most of the time?  It should be 1 44 1 44 1 44....

[Dennis_Knutson]

You really need to understand the fundamentals. If your widget is sending two hex bytes, a serial connection at the other end is not going to be reliable. The receiver is asynchronous to the writer and you have no idea of the byte order. You can use hex with a header/terminator but the sender code must make sure that these characters never show up in the data. The other option, as has been suggested, is to send the ASCII data with a terminator. Either way, it is the fault of your sender code.

[jonathangt923]

I'm very new to labview, so all of this is quite new and i am trying to understand as best I can.  I am now trying to send ASCII characters B then C with the termination character A after B and after C. see attached.  This is the graph i am getting: (also see attached). 

[Dennis_Knutson]

Your c code does not make any sense to me. What is a, b, c supposed to represent? What is usually done on the sender is converting to ascii representation of the numeric.

[jonathangt923]

what do you mean by ascii?  symbol representation? hex representation? decimal representation?  How i understand it is that ASCII is symbols/characters so A is ascii, which is 0x41 or 65 in decimal.  What should i send? A, 0x41, or 65?

[Dennis_Knutson]

Sending "1" + "." + "2" as text - 3 bytes for example. The termination character is usually a carriage return or line feed - one byte. This requires sending more bytes but it is clearer and easier to translate at the receiving end.

[crossrulz]

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@jonathangt923 wrote:

what do you mean by ascii?  symbol representation? hex representation? decimal representation?  How i understand it is that ASCII is symbols/characters so A is ascii, which is 0x41 or 65 in decimal.  What should i send? A, 0x41, or 65?

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http://www.asciitable.com/