Serial port empty read buffer

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• Store data from the Serial Port in the buffer and then take action?

  Hello! Everyone,

  I'm new to LabVIEW and I take assistance from various videos and stuffs available online to get started with LabVIEW.

  But I have a duty, therefore needing help.

  initially I see some of the tutorial videos and learned about the LabVIEW interface, and does a little project to communicate with the Port series (receiving and sending data).

  Happens to my task.

  My LabVIEW application will send a few State request packets on my device or control and based on the response packet that I have to display values.

  The Structure of package is as

  Header, length, Op_Code, data Checksum

  There is no terminator as newline or carriage return or anything else.

  In C language, I read the data from the Serial Port, and based on the length, I conclude that I got the full package or not, and then by recalculating the checksum value, the integrity of the package is verified and then based on that Op-Code has been sent will be decided.

  (I'm dealing with hexadecimal data)

  But how can I do this in LabVIEW.
  A tutorial or any referece will be useful for me.

  1. I suggest that you learn to use Shift Registers instead of local and global variables.  They are much more efficient (memory and execution speed) and make it much easier to read the schema.

  2. you don't need this inside the loop property node.  Is there a way to configure a Serial Port to turn off the stop character.

  3. you don't need to wait for playback VISA will limit the rate of loop if no data is coming.

  4. Once you have the length, you simply read the rest of the entire message and process it at a time.  This will make things a LOT faster.

  5. you should really do this enum a def type so that you can ensure that all your enum constants have the same values.  If you need to add a State later, simply update your enum in the same place then.

  

• communication serial port to read from an Analog Devices inertail sensor

  Hi, I have an ADIS16350 of inertial sensor by Analog Devices. My motive is to read continuous data of the sensor. Firmware sensor has specific commands as follows:

  Wil returns OK

  RA read a time of sensor

  It's going to read the sensor continuously

  When I try this in hyperterminal, everything works fine.

  However, I tried in the same method labview. However when I send no matter what this command the façade shows an error message. That means if I send 'at' command, instead of return 'OK' I get "ERROR: 61-74-30-43-error" in my opinion, this is a mistake sent by the firmware of the sensor. However just to test the system, I tried to send the command "continuous acquisition" of my program, LABVIEW, LabVIEW close, open Hyperterminal. To see the data is received at the Hyperterminal.

  Did someone come acroos a situation? Your comments are greatly appreciated.

  Thank you!

  Stéphane

  Check the stop character that you send with your order.  It is \r return (hex 0D dec 13) of the distribution or the new line/newline (hex 0A dec 10) \n?

• Serial Port problems - carriage return and use as an executable file

  Hello

  I developed an application to send a few simple commands on the serial port and read the corresponding answers of a device that I am in communication with.  I have been using logical Port to watch the line TX of the serial port.

  By using the Visa configure Serial Port I set the stop character property allow true and used the hexadecimal value D trying to make the termination a carriage return characters.  When I sent the order, I'll send the cmd followed by Enter.  No matter if this property is set to true or the hexadecimal value is set to D for carriage return or line break is, the serial port would always send a line break.

  Then I got crafty and the string constant under normal display to hexadecimal display.  The ONLY way I could send a carriage return was manually putting 0x0D after ordering.  So my question is, why the Visa set up the Serial Port is not working correctly, and is there a better way to send a carriage return?

  My next issue is facing the construction of executable files.  I'm using LabVIEW 8.2 and wrote this program for another employee to use on his laptop computer.  I did install runtime Labview 8.2 and led to the executable that I generated.  I did-> the executable by clicking Tools build the executable.  The problem I noticed was that the executable would open and will work perfectly, but it would not send any data the serial port.  I then ran the executable on my laptop (which contains the full version of LabVIEW 8.2) and the serial port has worked well.  I guess my question is... Are there plug-ins that must be installed to use the serial port with the Labview runtime engine?  Or y at - it a step that I failed to do?

  Thank you

  Gary Still

  Not immerse in the first issue. The Knight will probably be galloping until shortly.

  For your second question, after building the executable, you must build the installer and includes support for the VISA. VISA is required for serial communication, and it does not accept American Express.

  It may be useful

  -AK2DM

• Serial port buffer - how to read the last entry?

  Hello

  I'm trying to read data from a device connected to the serial port. The instrument makes a row of data, last updated CR LF at pre-set intervals (0.2 seconds, 0.5 sec., etc.). I want to read the most recent line to an interval of time different (for example 1 s). What happens is that the buffer fills, and when I read that I always get the whole buffer content, starting with the first (oldest) row of data.  After reading, I empty the buffer to prevent overflow.

  From the red string I, I serach occurrence of CRLF and take the data before the game. This will give me the first line of data (oldest), sometimes incomplete.

  What I want is the last line. There must be an easy way to achieve this?

  I can't use the Frother with my instrument.

  Any help appreciated

  Sylvester

  To give an idea, put something like this you diagram:

  

• reading serial port constantly and update the string buffer

  Hi guys,.

  I am facing a problem in reading the data in series using LabVIEW.

  I have an unknown size of data to be read on the RS-232 (Serial) and using read write serial.vi (example) I have read the data permanently and monitor for chain DONE on the buffer, but the channel indicator that displays the output not updated data.

  Chain should:

  1 2 3 4

  5 6 7 8

  I don't see one character at a time on the indicator.

  This is the screenshot of the vi

  

  Is there any method which will help me to do this?

  Hi Dave,.

  Thanks a lot... you helped me finish all my work... "Always small things blink quickly.

  See you soon,.

  Sailesh

• Problem: read bytes to serial port

  Hello, I need to communicate with an external device with serial port. I have to write a command to my device string, and then it should play with 64 bytes of data. I built a function of READING-WRITING and I use it in a loop (I have to read a lot of 64-byte block)

  Sometimes, I have the following problem:

  (1) I have send the command string, I wait with "Bytes to the serial port" whereas I have more then 60 bytes, then I read.

  (2) sometimes happen that the read function cannot read all 64 bytes, so the net for cycle, I have in the receiver buffer mor than 64 and the program to stop working. (does not work well)

  I need to be sure that after writing the command I have 64 bytes, so I red all the 64 bytes so the next loop for, I have the buffer of the empty receiver.

  I enclose my writing reading function. Please refer to the block diagram (there are a few notes).

  Thank you

  In no place in your program see the VISA configure the Serial Port. It's always a good idea to include this that even if you use the default settings. I suspect this is one of the default settings which is wrong with you. By default, playback is set to end when a character is considered. This means that if you have a 10 hex (ASCII LF) in your stream, playback stops until the specified number of bytes is read. Put in a VISA set up the Serial Port and connect a constant False to the stop character allow entry.

• Parity errors & read on Serial Port framing

  Hello, I am writing a program that reads the serial port IR thermometer. Intermittently I get parity so many framing errors and can't explain why or find a way to remedy. All the parameters of the series were double checked and controlled. I don't get any errors when you use HyperTerminal yet, when I do test bed in MAX, I see these mistakes from time to time. I tried the suggestions of the knowledge base for these as presenting a delay between the Visa set up and read the Visa or flushing buffer issue before reading, but none worked. Any idea or ideas would be appreciated.

  In addition, while searching through discussions on parity and framing errors, I saw a when a user recommends the following: "use wait event triggered by the stop character and when the error occurs, I just deleted the error, empty the buffer (wait the next stop character) and reread." If that sounds like a good solution, how would I go about its implementation?

  I've attached a screenshot of my reading series loop so you can see what I'm doing. I do about the error code control timeout is.

  Given that you have activated the stop character, you should not use the bytes to the serial port. You shouldn't have to delay or any function buffer flush.

  PS, You also have to change the way your loop exits.

• How better to apply a data serial port FIFO buffer?

  Hello

  I think I'm missing something very basic, so, please forgive my ignorance. All I want to do is to establish a simple FIFO buffer that has a logical sequence of quality control before the display of the data on the screen. I can't understand how best to continuously browse incoming data.

  The attached vi should explain much of it. My 25 bytes per second through the serial port of watercourses of the instrument. I heard it is best to put the VISA reading outside the loop, but I can't get my vi to read constantly new data if I do this (it stops at the length of the buffer specified).

  Is a possible solution to properly use a feedback node?

  Thanks for the help. I use LV2009.

  Use these settings

  

• Serial port receive buffer overflow error

  I am trying to send a file to a folder in my computer to another folder in the computer using conncections tcpip as part of me learning labview. But I get an error

  Possible reasons:

  LabVIEW: Serial Port receive buffer overflow.
  =========================
  LabVIEW: The network connection was refused by the server.

  I don't know how to fix this. So please help me. I have attached the VI here. Thanking you,

  You read just 1 character of the file.  With your read file, on behalf of the value-1 to read the entire file.

  In addition, for writing file, there is a Boolean input on top for 'Prepend/string Size array.  The value FALSE or you will get some additional data at the beginning of your file you want.

• serial port read one character

  Hello

  I'm new to the forum, so I don't know if I'm posting this question in the right place.

  However, my problem is I'm trying to communicate via serial rs-232 port and the goal is to read and write the question (code) of the device.

  The Unit regularly sends a "perpetuate" character S. When I read this character, I write the question and receive the response. Then a S appears again and I bravado the code, read the answer and so on...

  The problem is that when I try to do everything at once (read S, send the code and read the answer) and it 14 times before reaching the 1st code again once, labview is very slow. (3-5 seconds to perform this tasks 14 and restart the process). I think that the program becomes slow because that way I'm not using all the S which inflamed the writing and reading process.

  So, I wanted to read character by character (byte-by-byte) and then create a table with the answer. The problem is that the buffer sends answers with several bytes and I can't build an array in 'real time', beacause if I read (read VISA) only one byte, then I would be lost all the others.

  I think that chains concantenate and shift registers are part of the solution, but I have too many problems until I get to the part.

  So, please help me to read a single character and doesn't lose not the other bytes sent by the buffer, in order to fix the process, because I want one second per second refresh. The device emits a flow rate of 19200 baud.

  Thanks in advance

  I think that if you connect the value 1, the reading serial port function, you will receive a byte, and you won't lose the rest.

  The rest are stored in the buffer. If you use the previous function again, you will get the next byte.

• When a character appeared reading serial port

  How to wait for some specific characters occurred in the serial port (e.g. port COM1 RS232 on PC) and then they recover at the port?

  I want to communicate back with a motor controller that uses ASCII strings such as commands and responses. It formulates a response to any command sent, and the response contains exactly a termination character (that I can specify during installation) at the end of the response string. Sometimes also, it sends a message when there is no order issued, for example a disc error message. There is no simple way and reliable when the controller is going to speak, when he won't, and the message will be exactly how many time, but we do know that each message will have this stop only at the end character. I would like to interpret the entire message in my code, that is to say, I would like to retrieve the string of all the characters from the previous endpoint character up to and including the most recent stop character. I think it means that I would have a VI that returns the message string and does not stream until the stop character appeared and was added to the response string. Or, Alternatively, a loop that adds entire messages to a queue of strings.

  All the screw example I found seems to rely on a certain number of milliseconds to wait or to know how many bytes to read, in order to use VISA Read.

  So far, I use a loop which seeks bytes in the buffer, retrieves everything to add to a string of shift register and test if there is a character of the string endpoint, all extract up to and including the stop character, if so. This feels very awkward and expensive for what should be a common task. Is this general law approach, or did I miss something in a simpler way?

  I read on the communication by Message and characters of endpoint, approach that sounds functionally similar to this, but it seems around standards of SCPI and my motor controller does not support this. In any case example Finder does not get a single hit on 'Message '.

  Thank you!!

  It really looks like you are doing things a lot more difficult it must be. Look at the VISA configure Serial Port. It has a character of endpoints allow and end characters entries. If you wire a real (or leave that he unwired) entry activate, read VISA will end automatically when you specify the stop character is detected. As long as the number of bytes to read is larger that the largest string that you expect to read, there is nothing else you need to do. That's how examples of shipment are put in place and discussions about the characters of the termination. Should there be nothing related to sustainable intensification of CROPS. If you do not get a message in your specified time-out, you get a time-out error.

• Sometimes the lost bytes, reading the serial port

  Hello!

  I'm reading the serial port data (flow rate 57600 baud rate) that works very reliable so that I do not open any other window

  or minimize/restore my window of the application during the program is running. Then a byte of incoming data will be lost.

  I get a string of 30 bytes each 50 m in most of the cases the first byte is lost, sometimes one in the middle.

  This occurs not only on a PC.

  Is this a problem of LabVIEW or Windows?

  Are there settings that can solve the problem?

  Best regards

  JK78

  I solved the problem.  

  There was a bug in my program who become visible only if a window has been reduced or restored.

  When there are two or more messages in the buffer VISA, the separation of the messages was incorrect.

  Array index corresponded to false so that the first byte of the second message was at the end of the first

  and so the second message in the buffer seemed incomplete.

  In normal operation, the playback loop runs so fast, never both messages are in the buffer.

  Thanks for all replies.

  JK78

  Either way, I work with LabVIEW 2009 and serial interface hardware motherboard. With XON/XOFF flow control

  is not possible in my application because all the hex values from 00 h to FFh may appear in a message.

• Time GPS, Position, Velocity.vi - error-1073807360 reading was held at node (arg 1) .vi property VISA set up a Serial Port (Instr)

  We receive information such as the Latitude and Longitude of a receiver Garmin GPS18xLVC via a serial port on our PC using LabView 7.1.  Successfully, I connected the GPS on the serial port and tested with HyperTerminal.  I tried reading GPS time, Position, Velocity.vi several times and still receive the following error message: error 1073807360 has occurred to the property node (arg 1) visa configure a Serial Port (Instr) .vi.  I think it has something to with the configuration of the VISA series under vi.  Any suggestions would be greatly appreciated.

  Thank you

  I understood the question, that I had with the time reading the GPS, the Position, the Velocity.vi.  The vi. "do not open" port com automatically and so I had to modify the NMEA GPS Subvi reading to first open the port (VISA open command) and then continue with other operations.  Once I did this it started to work very well.  I don't understand why this feature has been left out because it won't work without it.  I tested the code with a receiver Garmin 18xlvc and it seems to work fine.

• VISA from read/write to serial port - unable to implements several orders of writing!

  Hello

  I'm new to Labview and I'm reading from a pressure through a virtual serial port USB sensor. I am able to read the port when you use HyperTerminal

  The code sequence that I should write to the port in order to obtain measurements using hyperterminal is the following:

  ' *' (2A hex)-online start and the responses of the port by asking 'Command', I should then enter

  FF-online measurement select the port must ask the 'mode', so I should enter

  0 has-online measurement of high resolution mode and it was then that I should start receiving action.

  The port is always answer by errors when I write the start command or the FF one. I tried to establish a sequence stacked to write the three commands then read the port, I added some delay between the three of them, but it does not work.

  Now I made really simple and removed the stacked sequence and just put the three commands one after the other and try to remedy not to not on the code.

  I'm really stuck at this point, could someone help me please? I read a lot fo articles on the forum, but I can't solve this problem

  Thank you

  I have attached my VI and the SCP1000 documentation (I can provide other versions of my demo if necessary)

  The reason for your problem is a frequent misunderstanding even among experienced programmers. Take a look at this thread

  http://forums.NI.com/NI/board/message?board.ID=170&thread.ID=417750

  In your data sheet, then they return codes like 0xFF or 0x0A so has a single byte of average value. Then you in your-active code constant writing FF\n is so this equal to values in format hexadecimal 46460A and your instrument do not understand. But it will include FF0A. In order to solve your problem, you would type in \FF\n in your '-' chain helped codes. Remember too, if you type in \32 it will be converted to character 2 this being 0 x 32 50 decimals and code ASCII 50 is equal 2

  Take the time and change the display format of string between '-' display and Hex display and you will see the difference

  Hope this helps