Endless SerialPort Reading

Hello there!
I have implemented the code Kevin Le made and it works perfectly.
It is a windows form that allows you to configure, open, read, write and close a COM Port in a wonderful and straightforward way. All of that using the serialPort class.
Due to the nature of my project, I need not only to read it once (through the 'read' button) but to read it as long as I want continously. Basically, I'm receiving data in any moment and I need to be able to capture it and save it into a SQL database (Haven't
figure that yet). Right now, I'm able to capture the buffer by clicking the button and save the data to a .txt file. I just want to make the program an automatically reader.
Any idea?

You are looking for the
DataReceived event on the SerialPort class. Attach a delegate to that event and it will be called anytime there is data to read. When your delegate is called, then call the Read method

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My application hangs after 10 hours in the serialport read sub-vi. Why?

My application is programmed under LabView 5.1.1 on a windows 2000 platform.
I use a MOXA RS232 extending module with a B&B RS485- converter.
After 10 hours trouble-free working, the application, using semaphores, hangs in the serialport read sub-vi.
In the same constelation without RS485-converter, once the application hanged up in the serialport write sub-vi. After Restarting LabView I was still not able to access the serial port. So I had to restart the PC.

I am not sure, but it looks for me as some buffer overflow error.
Like you read or write something before it is ready.
Try to play with the lines like DTR and so on.
regards
PP
Isildur wrote:
>
> My application is programmed under LabView 5.1.1 on a windows 2000
> platform.
> I use a MOXA RS232 extending module with a B&B RS485- converter.
> After 10 hours trouble-free working, the application, using
> semaphores, hangs in the serialport read sub-vi.
> In the same constelation without RS485-converter, once the application
> hanged up in the serialport write sub-vi. After Restarting LabView I
> was still not able to access the serial port. So I had to restart the
> PC.

SerialPort Read Timeout

Anyone knows how to achieve SerialPort Read Timeout? Or in another way to say it, stop reading from the SerialPort.

Remove the Serialport listener Maybe !

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My goal is to constantly archive data to a local machine thru a Telnet connection. I receive a small amount of streaming data (25 bytes/second) thru a static IP address. The code that is attached is my attempt to
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Attachments:
MBB06RawTelemetry.vi ‏27 KB

I said stop the inner loop either when the
button is pressed (as you still have) OR there is an error. So look at
the status of the error wire and OR it with the stop button before
wiring into the inner loops stop terminal.
Ok. Clear now.
I'm not sure
why you'd be getting a stop/continue dialog for error 56 because I
can't see anywhere in the code that would cause the dialog to pop up.
Drop some more indicators on your error wires, or probes. Run with
highlight execution turned on. Do any or all of these things until you
can figure out where the error is occurring.
Ok. I can do this. More later if necessary.
I don't know
where ^@ would be getting generated from unless somehow the telnet
protocol is doing it. What you could do is put a case structue or
select statement in the middle of the string so that if there is no
error, the string value goes from the read to the file. If there is an
error, an empty string goes to the file.
What do you mean by "in the middle"?
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Buffered Reader, how to make a loop to terminate

Hello, the code uses each line from the input.txt and does whatever we want, it's termination condition is when the next line is null. But this fails to work if the input.txt doesn't have an emptyline after the last line, how to change the code to work for those files?
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Edited by: Odinn on Jan 10, 2009 10:19 AM

Odinn wrote:
Nop, say I have an input.txt file that contains
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3
4the code above won't work files that the end line isn't empty. It works for:
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<assume theres an empty line here>Edited by: Odinn on Jan 10, 2009 10:37 AM
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Odinn wrote:
the code uses each line from the input.txt and does whatever we want, it's termination condition is when the next line is null. But this fails to work if the input.txt doesn't have an emptyline after the last lineI don't think your logic is correct. A blank line at the end of a text file is not the same as a null, and in fact, it does not fail. If you run the code, you will see that you are not in an endless loop.

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How can I use interupts in Labview

void main() {
while(1) { // the program wil work forever
if( button_Send == true) // the program wil execute send if the 'send button' is true
send();
else // if the button is false the program will read
read();
void serial() {
blabla...
void read() {
wait for character...
blabla...
this is what I made but as you might understand the program will hang in the read loop if theire is no character
to receive. this is what I had in mind but how can I do this in LV? I read something about vi prioreties...
anable interupt at serial port: // enable interupt
if( RXADRESS /= 0 ) { // chack if read buffer is not empty
void read(); // then read.
void main() {
while(1) { // the program wil work forever
if( button_Send == true) // the program wil execute send if the 'send button' is true
send();
else // if the button is false the program will wait for the
// send button or the interupt to accure
nothing..
void serial() {
wait for serial line to clear...
send char...
void read() {
if( RXADRESS /= 0 )
wait for character... // check if the read buffer is not empty
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Hi Memmo,
I assume when you say "Lightbold", you mean the highlighting tool in the LAbVIEW development environment.....
I also don't know if you have now implemented the serial communication in LAbVIEW or some other language, but I'll assume you've implemented it in LAbVIEW.
A typical reason for code working in "slow-mode" and not at full speed is some kind of timing problem within the code.
One suggestion I have is to first check the serial receive buffer before reading from the serial port. You can do this using the "Bytes at serial port" property of the VISA connection (I strongly advse using VISA if you're not already doing this). By wiring the "number of bytes" in the buffer to the read function, you only actually read what's already there. This way you skip the endless serial reads when nothing is there to read.
Since you are now looping a serial buffer query instead of getting stuck in a serial read dead-end, you can incorporate a stop criteria in your read loop (Either a stop button or a timeout). This should solve the problem of your program becoming non-responsive in the case of no data being sent to the serial port.
As to why exactly you are not always receiving the correct text, without code to look at, it's kind of impossible to guess where the problem might be. If you could post a picture of your block diagram, I'm sure someone can help pretty quickly.
Hope this helps
Shane.
Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)
Attachments:
VI example 2.png ‏11 KB

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Endless SerialPort Reading

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