Reading/Writing character commands to serial connection

Hey! I'm currently working on a project where part of it is to write a labview program to read and write commands through a serial connection to our PIC24F16KA304 board.
I basically have no knowledge on labview, I've been messing around on it for a few weeks trying to get myself familiar with it but I'm not having much luck.
Essentially I'm programming a train simulation control box. The PIC board will have a sensor that is connected to a train track that sends the character 'A' (for arrived) when a train stops at the station to lab view. I then want to be able to tell Labview to turn a LED on relevant to the station and then respond with the character 'M' for move. I need to repeat this situation for 6 stations
I also need to be able to 'R' for reversing the simulation, 'J' for jump (miss a station) and 'E' for end
If anyone with a bit more experience and knowledge then me can help I would be eternally grateful!

ChrissyC87 wrote:
I suggest that you read some of the LabVIEW basics: http://www.ni.com/gettingstarted/labviewbasics
A state machine would be a good starting point for this project (and your understanding of LabVIEW).
You can always wire constants to VI inputs on the block diagram instead of having controls on the front panel that you have to type into. Just right click on the VI >> create >> constant.
The LabVIEW basics will help you out with all of these simple problems.
Good luck,
-CC
Mega-Dittos!
My thoughts exactly. Adding to what Chrissy posted...
Your question reads like "How do I unlock the door to my car and win the Daytona 500?" The first part is simple (use the constants like Chrissy said) but the second part is much more invloved.
plese take the advise posted above and go thorugh the tutorials and learn to use state machines. AS yo udo this other questions will come up and you should feel free to start a new thread on ech question. Stick with it, play nice and we'll get you to the finish line.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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VISA Read gets incorrect data from serial connection

I am having difficulty using the VISA functions in LabVIEW to read data from a virtual COM port. Data is being sent from a serial to USB chip via a USB connection using OpenSDA drivers. I have a python program written to read from this chip as well, and it never has an issue. However, when trying to achieve the same read in LabVIEW I am running into the problem of getting incorrect data in the read buffer using the VISA Read function.
I have a VISA Configure Serial Port function set up with a control to select the COM port that the device is plugged into. Baud rate is default at 9600. Termination char of my data is a newline, which is also default. Enable termination char is set to true. A VISA Open function follows this configuration, and then feeds the VISA Resource Name Out into a while loop where a VISA Read function displays the data in read buffer. Byte count for the VISA Read is set to 20 so I can read more of the erroneous datat, however actual data will only be 6-12 bytes. The while loop has a wait function, and no matter how much I slow down the readings I still get incorrect data (I have tried 20ms thru 1000ms).
The data I expect to receive in the read buffer from VISA Read is in the form of "0-255,0-255,0-255\n", like the following:
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I have search but haven't found a similar issue and I am not sure what to try from here on. Any help is appreciated. Thanks!
Attachments:
Serial_Read_debugging.vi ‏13 KB

The first thing is that none of the error clusters are connected so you could be getting errors that you are not seeing. Are you sure about the comm parameters? Finally, I have never had a lot of luck looking for termination characters. You might want to just capture data and append each read into one long string just to see if you are still seeing this strangeness.
What sort of device is returning the data? How often does it spit out the data? How much distance is there between it and your computer? Can you configure it append something like a checksum or crc to the data?
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

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I've been assuming that when I do a file "open for access," that among the housekeeping functions set up behind the scenes, there is some sort of buffer created, the size of which is somehow related to the logical sector size of the disc in question, so that reading or writing short pieces of text, or even single characters, doesn't cause independent physical read/write actions at the disc drive.
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Hi Friend,
I reading the serial port one character at a time , i specified it in the "serial bytes to read" option in serial port read examples.
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Serial communication to read single character

Hi! List,
I want to read single character using serial communication(see the attached VI).
The initialization of the serial port is taken care.
TIA
Attachments:
Serial_comm[2_read_single_character].vi ‏42 KB

I'm not sure I can understand you. If you want to read just one single character why can't you do so by just passing 1 to the Serial Read function as the number of bytes to read?
The diagram of above VI doesn't make to much sense to me I have to admit.
Rolf K
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

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Hello.
I am working on a project where I have to write characters to a PIC in the style of a train controller that controls the direction of a train simulation.
I have the basic serial reading and writing working. Labview initially sends a 'S' to start the simulation on the PIC. Then it waits for the PIC to send characters relating to what station the train arrives at. Labview then lights the relevant LEDS on the front panel and then tells the PIC to move with a 'M'
However, I need to add some extra functions. I want to be able to send additional commands to the PIC such as 'J' to jump a station. 'E' to end the simulation and 'R' for reverse, so the train goes back a station instead of forward. I need these commands to be sent to the PIC when the 'M' is considered.
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Attachments:
Simulation2.vi ‏26 KB

Looking at your code more closely... why do you have your Start button wired to the "Enable Termination Char" input of VISA Configure Serial Port? That doesn't make any sense, nor does the comment next to it. Outside the while loop, why are you reading a local variable of each indicator and then writing that same value to the indicator terminal? That's not doing anything. It would be better to get rid of the local variables entirely. For example you could do something like this:
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James_G1 wrote:
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Alright I sorta got what you were sayin'. The code that I have now is:
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984429 wrote:
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