Efficient optimized way to read from serial port and GPS data display using map
Hi,
I have a custom h/w which reads the data from GPS Rx and after parsing send it to PC over RS232.
Each second it sends 201 bytes to PC. I have developed a VI to read the GPS data and display it. Project file is attached.
Fulctionality of different loops are as following:
1. LOOP 1: 1.1 Reads the serial data from com port.
1.2 Synclonize the frame using start bytes "a" and "z".
1.3 Reads next 4 bytes containg receiving error information.
1.4 Reads next 195 bytes. in which initial 80 byes are GPS data. rest are others.
2. LOOP 2: 2.1 Extarcts the GPS information and put them in an array.
2.2 Extarcts the receive error infor and counts the total error by incrimenting the variable using shift reg.
3. LOOP 3:3: 3.1 Displays the GPS data in chart and log the data in a file.
4. FLOW : Uses the GMAP .NET based API to creat a MAP and display.
Problem statement:
1. Functionality acheived.
2. However in between data set is being missed by the programm.
Quesitions:
1. Is the developed VI is efficient in terms of using queue loacl variables etc.
2. What are the improvments I can do to solve the problem.
Any other suggestions|
Thank you
jayant
jayant
Attachments:
Telemetry_Receiver_v2.zip 3075 KB
One of the most common problems in serial communication is the need for an adequate timing: how much time is expected your device to spend before answering? Have you put and adequate pause in your code before reading from the serial port?
Hope this helps
Roberto
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?
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A problem about reading from serial port
Hi,
I just sent '0x03' from MCU to PC continuously, and then sent '/n' as a stop character after every '0x03'. I use labview to read the data. The problem is when it get two '03' it get a '0', another two '03' and another a '0'. I don't know where is the '0' from?
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帖子被hengfo在08-08-2007 10:14 PM时编辑过了
Attachments:
serial read.vi 36 KBI think the problem may be the loop reading the serial port is running too fast. There is no timing delay in the loop, so you are reading it as fast as you can, and probably faster than the device is sending data. So sometimes the buffer is empty, and then the empty string gets converted to a numeric zero. The way to know for sure is to put an indicator on the error wire coming out of the serial port read. I bet you will see errors about the read buffer being empty.
Put a wait timer in the loop to slow down the execution just slightly. This is a good idea so that LV doesn't eat up all the CPU resources. Look at the example for Basic Serial Write and Read. You may want to have a loop ahead of the read that waits until there are a certain number of bytes at the port before it reads the serial port. You may want to put a loop around the serial port that waits until a valid number is read in before it exits the loop and goes to the numeric conversion.
Message Edited by Ravens Fan on 08-09-2007 08:50 AM -
Trouble reading from serial instrument and DAq simultaneously.
Greetings,
I am having some trouble getting my VI to read from my DAq and a serial instrument at the same time. If I run the subVI's simultaneously (i.e. subANG is running in one window and subVEL is running in a second window) both return the proper values and behave as I would expect. However, if I call the subVI's into a parent VI and try to run them both in the same loop structure subANG gets stuck and will not resond with a change in signal.
I have also tried to use a stacked or flat sequence to separate out the execution of subVEL and subANG, but I still get the no response from subANG.
The most confusing thing is that if I run Parent.VI in one window and then create a copy of subANG (call it '....-copy' or whatever) and run it in a second window, Parent.VI behaves properly and will refresh the readings as they appear in '...-copy'.
I have attached 3 files.
(1) subANG.VI -This reads an RS232 signal from an inclinometer. The signal is refreshed every 10ms or so.
(2) subVEL.VI -This reads raw voltage from one channel on the DAq, calculates the mean then converts that into a pressure differential and finally a velocity based on the pressure and temperature inputs.
(3) ParentVI.VI -This simply calls and displays the subVI's
My guess is that it is a buffer issue, but I am stumped. Does anybody out there in Labview land know why this might be happening? All suggestions welcom.
Solved!
Go to Solution.I am noticing it is not an NI DAQ card. How are you communicating with the DAQ? If it is using a serial port, that could be your problem.
I also highly recommend using the VISA drivers for serial communications instead of the serial.llb VIs.
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Plot more than one analog value to a waveform chart by reading from Serial Port
I have 4 LDRs and I want to plot their values to a waveform chart by reading them from the serial port. I have looked around and found an example of a VI plotting one value to a waveform chart (attached below) but I am unsure about how to expand this for 4 different waveforms, mostly because I don't particularly understand the way is being read currently. If someone could either point me in the way of a relevant example or explain/show me a solution, or explain howthe current VI I have works, that would be greatly appreciated.
Attachments:
LDRread.vi 20 KBSince I assume each LDR (whatever that is) has its own serial connection, you will need to read from 4 different serial ports. From there, just form an array of all the data and write to the chart.
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Hello
I am trying to build a VI that reads data (ascii values) from the serial port.
I am trying to build a wireless phonocardiogram. I have a microphone that acquires heart sounds. these signals are amplified and sent to a A/D converter to digitize them. the digital signal are sent to a base unit. The digitals signals received at the base unit have to be sent to a computer (over a serial port to view them).
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Thanks in advance.....
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Go to Solution.Hi chaitu209
What is your transmission speed, samplerate, and bandwidth needed in your project? The bandwidth of the serial port is somewhat limited. Let me give you an example
Say you are using 115200 Kbit per second as transmission speed, one start bit/stop bit and parity bit, and 8 bit data. This will give you 115200/11 bytes pr second as the maximum theoretical transfer rate/sample rate. But if you are using up to 16 bit AD your maximum samplerate will be 115200/(2x11). So my advise to you is to use a binary transfer protocol not ASCII based protocol. This is not a problem in Labview with serial transmission.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
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Computer freezes while reading from serial port
My computer freezes when i tried to read from a serial port for a longer period of time such as 10 hours. I always close the serial port after reading. please, help me solve this problem
I too experienced a similar problem twice on my machine and I have no idea how to stop it because it is so intermittent and I cannot replicate it.
Perhaps I can offer some clues.
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Function for reading from serial port
Hi experts,
We are trying to read data from the serial port with the following function we got from internet.
The problem is when creating the object with the sentence CREATE OBJECT o_obj '"MSCOMMLib.MSComm.1"'.
This returns a sy-subrc = 2 and shows the exception NO_CREATE_OBJECT.
We already copied the file MSCOMM32.OCX in c:\windows\system32 and we successfuly registered it, with regsvr32.exe.
We tried it with Windows XP and Vista.
Anybody has any idea?
Thanks in advance
FUNCTION ZSERIALCOM.
""Interfase local
*" IMPORTING
*" REFERENCE(MODE) TYPE I DEFAULT 0
*" REFERENCE(COMMPORT) TYPE I DEFAULT 1
*" REFERENCE(SETTINGS) TYPE C DEFAULT '2400,N,8,1'
*" REFERENCE(OUTPUT) TYPE C OPTIONAL
*" EXPORTING
*" REFERENCE(INPUT) TYPE C
*" EXCEPTIONS
*" NO_CREATE_OBJECT
TYPE-POOLS: sabc.
INCLUDE ole2incl.
PERFORM init.
PERFORM open_port USING commport settings.
IF mode = 0.
PERFORM read_port
CHANGING input.
ENDIF.
IF mode = 1.
PERFORM write_port
USING output
CHANGING input.
ENDIF.
PERFORM final.
ENDFUNCTION.
DATA: o_obj TYPE ole2_object.
*& Form Init
text
--> p1 text
<-- p2 text
FORM init.
DATA:
wa_repid LIKE sy-repid.
wa_repid = sy-repid.
CALL FUNCTION 'AUTHORITY_CHECK_OLE'
EXPORTING
program = wa_repid
activity = sabc_act_call
application = 'MSCOMMLib.MSComm.1'
EXCEPTIONS
no_authority = 1
activity_unknown = 2
OTHERS = 3.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
CREATE OBJECT o_obj '"MSCOMMLib.MSComm.1"'.
IF sy-subrc <> 0.
RAISE no_create_object.
ENDIF.
ENDFORM. " Init
FORM open_port *
--> COMMPORT *
--> SETTINGS *
FORM open_port USING commport settings.
SET PROPERTY OF o_obj 'CommPort' = commport.
SET PROPERTY OF o_obj 'Settings' = settings.
SET PROPERTY OF o_obj 'InputLen' = 0.
SET PROPERTY OF o_obj 'PortOpen' = 1.
ENDFORM. "open_port
FORM read_port *
--> INPUT *
FORM read_port
CHANGING input.
DATA:
wa_buffer TYPE i.
DO 10 TIMES.
GET PROPERTY OF o_obj 'InBufferCount' = wa_buffer.
IF wa_buffer > 0.
GET PROPERTY OF o_obj 'Input' = input.
EXIT.
ENDIF.
ENDDO.
ENDFORM. " read_port
FORM write_port *
--> OUTPUT *
FORM write_port
USING output
CHANGING input.
DATA:
wa_buffer TYPE i.
SET PROPERTY OF o_obj 'Output' = output.
DO 10 TIMES.
GET PROPERTY OF o_obj 'InBufferCount' = wa_buffer.
IF wa_buffer > 0.
GET PROPERTY OF o_obj 'Input' = input.
EXIT.
ENDIF.
ENDDO.
ENDFORM.
*& Form final
text
--> p1 text
<-- p2 text
FORM final.
SET PROPERTY OF o_obj 'PortOpen' = 0.
FREE OBJECT o_obj.
ENDFORM. " finalbligwHi ,
I want to read value form weigh bridge through COMM port. I have developed the FM and done the setting as mentioned in the below link
Read COMM port using ABAP w/o third party software
but while executing the FM independently I am able to get the value from the COMM port,but when I call the FM from a program I am not able to get the output value from the FM.I am calling the FM from the report program.please find the code below.
report test.
data : lv_input TYPE c.
CALL FUNCTION 'ZFM_WEIGHINTERFACE'
EXPORTING
MODE = 0
COMMPORT = 1
SETTINGS = '1200,N,8,1'
OUTPUT = ''
IMPORTING
INPUT = lv_input
EXCEPTIONS
NO_CREATE_OBJECT = 1
OTHERS = 2
IF SY-SUBRC <> 0.
* Implement suitable error handling here
ENDIF.
if I execute the FM independently the output is getting perfectly.but while calling from a program i am facing the issue..
any suggestion is appreciated.
Thanks
Vivek -
Controlled reading from serial port
I'm trying to establish a connection to an external device through the serial port. This is done in a while-loop which sends an association request tries to get a response if a response is not recieved a new rewuest is sent, etc. At the moment this procedure does not work. I am considering two explanations for this. The first is that the loop does not wait long enough for a response to come and simply keeps pumping out requests, the other is that there is something wrong with the reading algorithm, that doesn't let it properly take in information from the serial port.
Solved!
Go to Solution.
Attachments:
association_loop.GIF 5 KB
read_visa.GIF 8 KBI made a new version of the read case. The old version was a while loop, the new version is a while loop which will go on until it encounters an EOF character. In this case it is
0xC1 or 'Á'. I thought the old version would break before getting any message. This doesnt get any signal either. I have probed it, and it doesn't get a string from which to take the length.
Attachments:
read_visa2.GIF 10 KB -
HI,
I need to read data from virtual serial (rfcomm - BT GPS receiver). I connect to my gps using system command:
[root@localhost ~]# rfcomm connect /dev/rfcomm0 XX:XX:XX:XX:XX:XX
and this creates port at /dev/rfcomm0, when I do :
[root@localhost ~]# cat /dev/rfcomm0
I get:
M,0.0,0000*76
$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05
$GPRMC,000009.999,V,0000.0000,N,00000.0000,E,,,101102,,*17
$GPGGA,000010.999,0000.0000,N,00000.0000,E,0,00,50.0,0.0,M,0.0,M,0.0,0000*7E
$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05
and the only problem is what to do to read this sequences via java application. I obtained package comm2.0.3.zip , but have no idea what next. I would be grateful for any help.
best regards
joshuaI did everything described here:
http://www.geeksville.com/~kevinh/linuxcomm.html
got an example from:
http://java.sun.com/developer/releases/javacomm/SimpleRead.java
(the defaultPort = "/dev/term/a"
replaced with
defaultPort = "/dev/rfcomm0")
i connect to my gps with:
[root@localhost ~]# rfcomm connect /dev/rfcomm0 XX:XX:XX:XX:XX:XX
start the application and get an error:
java.io.IOException: Error instantiating class gnu.io.RXTXCommDriver
gnu.io.RXTXCommDriver cannot be cast to javax.comm.CommDriver
at javax.comm.CommPortIdentifier.loadDriver(CommPortIdentifier.java:239)
at javax.comm.CommPortIdentifier.<clinit>(CommPortIdentifier.java:109)
at comm.SimpleRead.main(SimpleRead.java:78)
Exception in thread "main" java.lang.UnsatisfiedLinkError: com.sun.comm.SunrayInfo.isSessionActive()Z
at com.sun.comm.SunrayInfo.isSessionActive(Native Method)
at com.sun.comm.Portmapping.registerCommPorts(Portmapping.java:155)
at com.sun.comm.Portmapping.refreshPortDatabase(Portmapping.java:100)
at javax.comm.CommPortIdentifier.<clinit>(CommPortIdentifier.java:138)
at comm.SimpleRead.main(SimpleRead.java:78)
Java Result: 1
i think i did everything about rxtx as described. could anyone help?
best regards
joshua -
I already stablish communication with my serial port using VISA, selecting COM1 as the resoure name.
After that, I tried to read the data from the port (as we know the data was in string format )but I need to convert the data to numeric value to hadle it (no arrays).
Another main thing is that I'm develoing a new based Embedded design and tthe info that will trhow out from the device to the PC is binary.
How can I solved the problem, and if I want to make bidirectional communication with my system how can I do it? The VISA intructions as *IDN? and so forthetc can be recognize by the external system if the COM1 port is recognized by NI Max as ADSRL1::I
NSTR1?Hello,
For an example of bidirectional serial communication in LabVIEW, please see the shipping example LabVIEW <-> Serial.vi. This can be found from LabVIEW by going to Help >> Find Examples. From the example finder, select Hardware Input and Output >> Serial >> LabVIEW <-> Serial.vi.
Once you are able to read the string data in, you can use the VIs in the String/Number Conversion palette to convert the data to numeric format. To access these, right-click on the block diagram >> All Functions >> String >> String/Number Conversion.
Let me know if this does not help.
Regards,
Sean C.
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Using servlets to read from text file and insert data
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Can I use a servlet to read from a space delimited text file on the client computer and use that data to insert into a table in my database? I want to make it easy for my users to upload their data without having to have them use SQL*Loader. If so can someone give me a hint as how to get started? I appreciate it.
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I suppose that Camera Raw 8 hosted in Bridge CC as well as Lightroom 5 are suffering from the same issue.Nobody? Absolutely nobody?? Zalman? Eric? Anyone?
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How to decode a set of datas received from serial port and display image on a canvas based on CVI ?
Hi !
I have received a set of datas via rs232 and it contains picture messages. I have to decode the datas first and then display them on a canvas.
I have known several functions that may be used . Such as
int SetBitmapData (int bitmapID, int bytesPerRow, int pixelDepth, int colorTable[], unsigned char bits[], unsigned char mask[]);
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int bytesPerRow, int pixelDepth, int colorTable[], unsigned char bits[], unsigned char mask[]
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Attachments:
Decode and display image.zip 212 KBWell, things are getting a bit clearer now.
1. Your image is actually 240x240 pixel (not 320x240 as you told before). The size of image data is 57600 bytes which corresponds to that frmat (I was puzzled by such a data size compared with larger image dimensions!)
2. The image is a 8-bits-per-pixel one; this means that you must provide a color palette to create the bitmap
3. You cannot simply copy image data into bitmap fields in CVI: CreateBitmap always produce an image with pixeldepth matched with display colour depth (normally 24 or 32 bpp)
All that means that you must:
1. Create the appropriate color palette with 256 colors: it may be a grayscale or color palette depending on camera characteristics. Grayscale palette can be found in my sample project, while sample colour palettes can be found here (here the description of a "standard" 8-bpp color palette)
2. Create the bits array correctly dimensioned for the color depth of your monitor
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Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos? -
Read from txt file and analyse data
hi,
i am having a problem for reading data from a text file and checking whether it is a integer or not.
basically if i have a txt file with the following content:
12 45 345 500 45.67684 33
my output should be:
12 45 345 500 invalid 33
that means if there is a integer number in the file, the integer number will be printed on the screen BUT if there is anything else like a string or a double number, then "invalid" will be printed.
how can i check what kind of datatype it is??
i have the following code to start with:
try
BufferedReader in = new BufferedReader(new FileReader(FileName));
String l = in.readLine();
in.close();
catch(IOException e)
System.out.println("IO error");
System.exit(0);
}ok i have tried the following code:
int index = 0;
String[] arr = null;
int nb = 0;
try
BufferedReader in = new BufferedReader(new FileReader(nameFile));
String line = in.readLine();
arr = line.split(" ");
for(int i=0; i<arr.length; i++)
index = i;
nb = Integer.parseInt(arr);
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which works perfectly fine for the following scenario:
txt-file:
12 45 345 500 45.67684 33
output:
12 45 345 500 invalid 33
but what, if I have the following data in my txt file:
12 45 345 500 45.67684 33 23.234 21
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Reading a char array from Serial port
Need help!
Hi, I've got the following problem - I wanna read a input stream from serial port and I use at the moment the following method (reading bytewise):
public String receiveText (){
byte ch;
fStrBuf.delete(0,fStrBuf.length()); //clearing the buffer
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fStrBuf.append( (char) ch);
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return fStrBuf.toString();It works pretty well, but disadvantage is that it's too slow to use it in the thread (at least I think so)
How can I change it to read all available data from the port (or simply faste). I don't need event listeners, because it's a request-responde communication.
I tried smth. like this
byte[] readBuffer = new byte[20];
try {
while (fPortInStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
fStrBuf.append(readBuffer);
} catch (IOException e) {}
return fStrBuf.toString();But it doesn't seem to work :-(May I suggest that you use StringBuilder rather than StringBuffer. It has less overhead because it is not threadsafe. I do synchronous serial port stuff with Opto 22, and i have no listeners enabled.
Appending to the String(Builder/Buffer) directly from the byte buffer mangles it. So I use a string (ugh). With the Opto22 brain boards, i am looking for a carriage return as a term char. It either finds it or times out.
This is the best i have come up with so far:
StringBuilder response = new StringBuilder();
String data = new String();
long msTimeOut = 2000;
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byte[] readBuff = {0};
int charAvail;
response.delete(0,response.length());
long ts = Calendar.getInstance().getTimeInMillis();
try {
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charAvail = inputStream.available();
if ( charAvail > 0 ) {
readBuff = new byte[charAvail];
inputStream.read(readBuff);
response.append(new String(readBuff));
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break;
} catch (IOException e) { e.printStackTrace(); throw e; }
data = response.substring(0);
} I just starting writing Java about 4 days ago, so caveat emptor.
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