Get bytes available at serial port
I'm using the CNiVisaSession wrapper class for serial communication. Is there a way to get the number of bytes available at the serial port using this class like there is with the ActiveX object CWSerial.GetBytesAtPort() method?
Thanks,
Lyle
Yea, you just call GetAttribute on the object with an attribute of VisaSerialBytesAvailable, its a uInt32.
Best Regards,
Chris Matthews
National Instruments
Similar Messages
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Writing bytes out of Serial Port
I'm trying to write an array of numeric (U8) bytes out of the serial
port. The serial routines though only support strings. Labview has a
routine which converts U8 into strings but only upto x7F (which is the
limit of ASCII) and not to xFF.
Anybody have a workaround to this ?
Thanks.I just tried the "byte array to string" function (under "conversion"
subpalette under "string" subpalette) and did not see this limitation.
You can put an array of U8 on the front panel, change the format to
display Hex, and type any hex code 0 to FF, and send this thru "byte array
to string" and then through "string to byte arry" to get the original
array back. Create an indicator for viewing the intermediate string and
pop up on the string indicator to change it to hex display. You will see
all the "characters" being translated faithfully.
- Vinny Recca
Ashish Khanna wrote:
> I'm trying to write an array of numeric (U8) bytes out of the serial
> port. The serial routines though only support strings. Labview has a
> routine which converts U8 into strings but
only upto x7F (which is the
> limit of ASCII) and not to xFF.
>
> Anybody have a workaround to this ?
> Thanks. -
How do I monitor serial port activity without first sending a command?
In my application I am sending a command through the serial interface and I want to monitor the response. The response is not instant, in fact it is a timeout response indicating the requested action did not work. How do I monitor so I can parse what is coming in over the serial port without necessarily sending a command?
You can always place a loop where you monitor the number of bytes at the serial port.
After configuring your VISA serial port session, you can create a Property Node to get the number of bytes available at serial port.
You can then process this information, for instance:
1. Establish a timeout because you never get a response.
2. Do serial port read if there is data available.
You can exit the loop with a timeout condition or having processed the data.
-JLV- -
0 bytes at serial port after Visa Write
Hi,
I'm having problems communicating with a Pollux box controlling a stepper motor (both from Micos). The Pollux box has an RS232/485 connection to the computer.
I have tried adaptations of LV's Basic Serial Read and Write example. Even for the basic example there has never been any bytes at the serial port after the write.
I have attached some sample code for LV 10.0.1(64bit) and the OS is Windows Server Enterprise 2008.
The Visa drivers have just been installed.
After some research I have added a 'Set I/O buffer size' as advised by http://digital.ni.com/public.nsf/allkb/60DDFED7EFEFE7188625705700750821?OpenDocument
The time-out is set to 10s, I have a wait of 1s before read and 0.5s between each write (the characters are written individually incase that was the problem).
The write command getaxisno_ should reply with the default axis no which is 1. However, there is never any reply.
The termination character for Venus2 is a space for transmitting commands and ASCII CR LF at the end of received data.
I'm not sure what else could be wrong. According to MAX the device is working properly. Although, when I try to open a Visa test panel in MAX the program crashes. I'm not sure if this is a related problem.
I'd be really grateful for any advice, have been trying to fix this for a few days now.
Thanks in advance!
Ciara
Attachments:
Getaxisno test.vi 18 KBThanks, I'll search those now.
When I click the test panel button, the Max window disappears and the program is closed. Next time I open it an Unexpected Error box opens with a message saying there was an unexpected error and I should search Info Code MAXKnownException.
'The exception occurred in the NIMax process in the function (Unknown).'
I have searched this and the info advised me to send a report with log files etc to NI which I have done. Just waiting on the reply.
I copied the Visa resource name from MAX and the termination character is the same as what a previous owner of the equipment used in Visual Basic. -
How to display raw, not ascii, bytes from serial port?
Hello, I have an instrument that outputs raw data, not ascii, bytes to a serial port. How do you display raw data, not ascii, bytes from a serial port? Since raw data bytes are not displayable, there is got to be something in labview to interpret/display the received bytes the way it is as data in HEX or Binary. The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place. For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code. I am using a VISA-RD function currently to receive the data from a COM port. VISA-RD outputs string type. Thank for any feedback or suggestion in advance.
BC@Baxter wrote:
...The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place...
Of course they are string type, just not formatted in a human readable form. So, YES, these functions are not appropriate.
BC@Baxter wrote:
For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code.
Dennis is right, but there is no "decimal" display for strings, so the second requirement needs a tiny little bit more code.
If you have a single byte string, you can typecast it into a U8 number and set the display format as decimal, hex, octal, or binary as desired. In decimal, it would display the number 77. Since it is now a numeric, you can even do math with it.
In general, the string has multiple bytes, and you would typecast it into an array of U8 numbers (Since this is an often used function, there is also a "string to byte array" which does the same thing).
Typecasting is the secret. You can e.g. easily typecast 2 bytes into a U16, 4 bytes into a I32, 8 bytes into a DBL, etc. For more detailed requirements, there is also the "unflatten from string". Check the online help for details. Good luck!
LabVIEW Champion . Do more with less code and in less time . -
How do I process serial port strings as bits
In response to my commands, my instrument is sending bytes to my serial
port. In one instance, 2 bytes are received. I want to treat these 2 bytes
as a group of 16 bits.
The VISA and Compatibility Serial functions return these bytes from the
serial port to Labview clearly labelled a "string".
Everything I can find in the way of Labview functions and .vis don't want to
do bit twiddling, bit swapping, and bit dropping, with "string" data.
I thought "hex string to number" could be used here, but I can't find a way.
The 2 Bytes in question can be represented as hex, but the data are not the
ASCII codes for the hex representation of a binary number, they are the
binary number. This "hex string to number" seems to want ASCII c
odes.
You can feed a hex number typed into a "control" box wired into "hex string
to number" and you get a meaningful number. You can feed the 2 bytes from
the serial port into an "indicator" set to read in hex and you get a hex
number that is a correct representation. But that is Labview handing them
around to itself. I need to get my "hands" on them.
I can't feed those same bytes that show up as a correct hex representation
in an indicator into the "hex string to number" or anything else, so far,
and get a number that is useful for further processing.
I thought "variant to data", but I can't find enough reference material to
understand how to use it. A boolean array seems like a bit of a weird
approach, so I thought I'd ask before I looked into that.
I'm used to dealing directly with binary numbers on the processor stack, I
call them whatever I want, and turn them into anything I feel like.
I'm sure I'm staring the solution in the face, but I can't find any way to
persuade
Labview to treat this "string" data as 16 bits.
I've got the 16 bits, which is better than not having them, but I don't have
much hair left.duh, well I finally discovered the "Unflatten from String" function. A guy
just feeds in the bytes he's collected from his serial port that Labview
thinks are a "string", and out come lovely little unsigned 16 bit numbers,
or whatever other type of number he wants to turn the bytes into. And there
are great little bit twiddlers available after that, like "swap bytes", and
you can mask out bits with the logic operators, why this is fun. There's
nothing like being a moron...... fly me to the moon...................
"David Lewis" wrote in message
news:[email protected]..
> The two bytes would come from a serial port read.vi in Labview, classed as
a
> string. For instance, D3 and 02. The output wou
ld swap the two bytes,
i.e.
> to 02 and D3, consider the two swapped bytes as 16 bits, drop the six most
> significant bits, and output the ten bits that are left as an integer
> classed by Labview as some kind of number, not a string.
>
> Your example StringToBits_Converter.vi I found on the ni.com site
> unfortunately gives an error message and refuses to open on my system
saying
> it comes from a newer version of Labview 6 than I am running. Mine says
> 6.0.1b3. Thank you very much anyway.
>
> "FightOnSCTrojan" wrote in message
> news:[email protected]..
> > In another words, you want to create a VI in which the input is 2
> > strings (i.e. AB) and the output is the converted array bits (e.g.
> > 1010101010101010)?
>
> -
How to transfer file from PC to PC via serial port using labview
I need to transfer files(.txt, .doc, .xls) from PC to PC via serial port using LabVIEW. Is it possible to transfer files, if so how to transfer?
Solved!
Go to Solution.Yes, it is possible to transfer files with the serial port using LabVIEW. Files are just collections of bytes and the serial port is pretty good at shipping bytes from one PC to another. You need to connect the serial ports together with a null modem cable.
First, take a look at the example for serial communication. In LabVIEW, go to the Help menu and select "Find Examples...". From there you can search for "serial" or navigate to Hardware Input and Output >> Serial. Select the "Basic Serial Write and Read.vi". Experiment with that example to gain confidence on the serial communication methods.
Next, it's time to learn about how to read and write files. For that, the examples could be somewhat confusing since they all deal with files that are presumed to have data of a specific type in them. I would recommend just getting familiar with the functions on the File I/O palette. Specifically, get to know the following functions.
Open/Create/Replace File - On your destination side, you'll need to create the copy of the file that you are trying to transfer
Close File - When you are finished reading from or writing to a file, you should close it. It cleans up the memory being used and finalizes any write operations that are still floating in the write buffer.
Read From Binary File - The best way to read from a file when you do not really care what type of file it is. In your case, you just want to get those bytes read and sent out so they can be written down at the destination.
Write to Binary File - At the destination side, this is what will store those bytes to the file you created with number 1.
Get File Size (under the Advanced File Functions sub-palette) - You need to know how big the file is so you know when you are finished.
OK, so once you are able to create files, write bytes to them, and read bytes from existing files you can move on to transferring.
The basic method I would suggest is to have the user specify a source file on the source PC and a destination folder on the destination PC. Then, find out the size of the source file using number 5. Divide that size number by the number of bytes you feel like transferring at once. The serial buffers are usually around 32k (if I remember correctly) so do not exceed that. Now begin sending data by reading some number of bytes and wiring that string output to the VISA Write function. On the destination side, you'll want to be monitoring the serial port for bytes and reading them when they arrive. Wire that string to the Write to Binary File function to add them to your destination file.
That is the basic outline of how to do it. You have to be careful not to overload the write and read buffers on the serial ports. Initially you can use delays on the sending side to make sure the reading side has enough time to digest. To get things moving faster, you can bring in some flow control.
If all that sounds a bit intimidating, there are Alliance Member companies out there (such as PrimeTest Automation) who can write such code for you and even provide a turnkey solution for you.
Happy wiring,
Dan Press
Certified LabVIEW Architect
PrimeTest Automation -
Serial Ports using HyperV in Ubuntu guest OS
I need to run a terminal session (term) from within the guest OS, Ubuntu 12.04.3 LTS to a serial port on the Windows 8.1P host. In my case a USB to serial adapter that Windows has mapped to COM5.
I don't really know where to start. In HyperV, under Settings, I see a Com1 and Com2 under hardware. The two options are None or Named pipe. Not all that clear what to do here.
Presumably this is what will be visible to Ubuntu as /dev/ttyXX ??
Can anyone point the way to map a serial port into Ubuntu? Or a suitable workaround?
Thanks."How can a VM be so cut off from the hardware like that?"
Well, for the most part, it's been a long time since I have even seen a machine with a serial port on it. It is so uncommon that one generally needs to buy an add-on card or do something like USB to serial. That trend has been going on for a
long time - that's why network based serial devices have tended to the solution for this. This is nothing new. Even Microsoft's Virtual Server, the precursor to Hyper-V (which was released five years ago) did not have access to serial ports.
Since you are asking in the Hyper-V forum, the answer is you can't get to a physical serial port on your host.
.:|:.:|:. tim -
Hello,
I would like to know how Serial Port in java works. I mean, I installed the javax.comm driver in windows and there is no problem.
However, what happens if I use 7, 6 or 5 bits of data in the serial port? The Java communicactions API provide an Outputstream to send data through serial port. So it only accepts byte [].
If I configure my serial port with 7 bits of data, how is it sent? I mean:
it sends only the 7 lower bits of a byte? If DATABITS are set to 5, 6, it sends the 5 or 6 lower bits of the byte?
Thanks
bramezThe number of bits that is defined does not affect the byte representation in Java system. It determines only the number of bits that will represent one byte between the serial port and the device that it will be connected to it , normally external modem will be connected to serial port.
If the number of bits = 7 , that means that the 8th. bit will be used as a parity so the Parity parameter should be Even or Odd , but if the data bits = 8, there is no parity. -
Jslider hammers my serial port
I'm trying to use a slider to send bytes over a serial port.
It sends data too fast. I use wait(n) to block an xmit method called by the slider event handler, and notifyAll() to re-enable transmission alright, but the nasty slider seems to cache some data before the method blocks, then continue to transmit.
How do I slow its firing?
Thanks!Some example code would have been nice
But hear is my two cents: Do know how you are sending the data but you could use a buffer strategy and instead of letting the slider function send the data directly, you could store it in some Vector (or Collection) and send it later using a Timer or some thread.
ICE -
Any way to communicate with Serial PORT using JavaScript
is there any way to communicate with Serial PORT using JavaScript ??
Dont tell me to do it in java because I need to this on client side not on server side.
such as when client pressed the button, a javascript function will be called and in that function I need to communicate with the serial port of that client... That action will not go to server side.Is there any way to send a string of bytes to the serial port from the client side ?
Just a button on the web page that sends out stuff to the comport.
I was hoping to do this using java script also .. -
How to get data from serial port to GUI textArea
From Serial Port.....
Messages from base (always 5 bytes):
0xAA, 0, 0, 0, 0xBB - IDLE Mode
0xAA, 0, 0x80, 0x80, 0xBB - Question Mode
messages from terminal (always 6 bytes):
0xAA, a, b, c, chksum, 0xBB
where chksum = a+b+c;
a = address (0-250)
the 2 MSB's of b represenet the answer:
0 0 - A
0 1 - B
1 0 - C
1 1 - D
the 6LSB's of b and 8bits of c is the time for answer, in milliseconds.
(0-16384 milliseconds)
I have VB Code for that but I want the same thing in Java ...
Can any one help me?
Here's VB Code..
VERSION 5.00
Object = "{648A5603-2C6E-101B-82B6-000000000014}#1.1#0"; "MSCOMM32.OCX"
Begin VB.Form Form1
BorderStyle = 1 'Fixed Single
Caption = "Aakar GUI"
ClientHeight = 4665
ClientLeft = 60
ClientTop = 375
ClientWidth = 6105
LinkTopic = "Form1"
MaxButton = 0 'False
MinButton = 0 'False
ScaleHeight = 311
ScaleMode = 3 'Pixel
ScaleWidth = 407
StartUpPosition = 3 'Windows Default
Begin VB.CommandButton cmdPort
Caption = "Open Port"
Height = 375
Left = 120
TabIndex = 4
Top = 600
Width = 1455
End
Begin VB.ComboBox cmbPort
Height = 315
ItemData = "Form1.frx":0000
Left = 120
List = "Form1.frx":0016
Style = 2 'Dropdown List
TabIndex = 3
Top = 120
Width = 2895
End
Begin VB.CommandButton cmdEnd
Caption = "End"
Height = 495
Left = 1560
TabIndex = 2
Top = 1320
Width = 1215
End
Begin VB.CommandButton cmdStart
Caption = "Start"
Height = 495
Left = 120
TabIndex = 1
Top = 1320
Width = 1215
End
Begin VB.TextBox txtMessage
Height = 2040
Left = 119
MultiLine = -1 'True
ScrollBars = 3 'Both
TabIndex = 0
Top = 2475
Width = 5848
End
Begin VB.Timer tmrRead
Enabled = 0 'False
Interval = 1
Left = 2040
Top = 600
End
Begin MSCommLib.MSComm MSComm1
Left = 3120
Top = 360
_ExtentX = 1164
_ExtentY = 1164
_Version = 393216
DTREnable = 0 'False
ParityReplace = 45
SThreshold = 1
End
Begin VB.Label Label5
Caption = "Result Data:"
Height = 375
Left = 120
TabIndex = 5
Top = 2115
Width = 1320
End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Dim PortIsOpen As Boolean
Dim Answers(4) As String
Dim RejectKeystroke As Boolean
Private Sub cmbPort_Change()
Debug.Print cmbPort.ListIndex
End Sub
Private Sub cmbPort_Validate(Cancel As Boolean)
'Cancel = True
End Sub
Private Sub cmdEnd_Click()
MSComm1.Output = "e"
txtMessage.Text = ""
End Sub
Private Sub cmdPort_Click()
On Error GoTo ErrorHandler
If cmbPort.ListIndex < 0 Then Exit Sub
If PortIsOpen Then
cmbPort.Enabled = True
MSComm1.PortOpen = False
PortIsOpen = False
cmdPort.Caption = "Open Port"
cmdStart.Enabled = False
cmdEnd.Enabled = False
Else
MSComm1.CommPort = cmbPort.ListIndex + 1
cmbPort.Enabled = False
MSComm1.PortOpen = True
PortIsOpen = True
cmdPort.Caption = "Close Port"
cmdStart.Enabled = True
cmdEnd.Enabled = True
End If
Exit Sub
ErrorHandler:
Debug.Print Err.Number
Debug.Print Err.Description
MsgBox Err.Description, vbExclamation Or vbOKOnly, "Error opening port"
cmbPort.Enabled = True
PortIsOpen = False
cmdPort.Caption = "Open Port"
cmdStart.Enabled = False
cmdEnd.Enabled = False
End Sub
Private Sub cmdStart_Click()
MSComm1.Output = "s"
txtMessage.Text = ""
End Sub
Private Sub Form_Initialize()
Dim tmp As Variant
tmp = InitCommonControls
End Sub
Private Sub Form_Load()
Answers(0) = "A"
Answers(1) = "B"
Answers(2) = "C"
Answers(3) = "D"
'MSComm1.Settings = "9600,n,8,1"
''MSComm1.Settings = "115200,n,8,1"
'MSComm1.PortOpen = True
On Error GoTo ErrorHandler1
MSComm1.CommPort = 1 ' comm port 1
MSComm1.RThreshold = 1 ' use 'on comm' event processing
MSComm1.Settings = "9600,n,8,1" ' baud, parity, data bits, stop bits
MSComm1.SThreshold = 1 ' allows us to track Tx LED
MSComm1.InputMode = comInputModeText 'comInputModeBinary ' binary mode, you can also use
' comInputModeText for text only use
PortIsOpen = False
cmbPort.ListIndex = 0
' open the port
MSComm1.PortOpen = True
cmbPort.Enabled = False
PortIsOpen = True
cmdPort.Caption = "Close Port"
cmdStart.Enabled = True
cmdEnd.Enabled = True
Exit Sub
ErrorHandler1:
Debug.Print Err.Description
PortIsOpen = False
cmbPort.Enabled = True
cmdPort.Caption = "Open Port"
cmdStart.Enabled = False
cmdEnd.Enabled = False
End Sub
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
If MSComm1.PortOpen Then MSComm1.PortOpen = False
End Sub
Private Sub lblOption_Click()
End Sub
Private Sub MSComm1_OnComm()
' Synopsis: Handle incoming characters, 'On Comm' Event
' Description: By setting MSComm1.RThreshold = 1, this event will fire for
' each character that arrives in the comm controls input buffer.
' Set MSComm1.RThreshold = 0 if you want to poll the control
' yourself, either via a TImer or within program execution loop.
' In most cases, OnComm Event processing shown here is the prefered
' method of processing incoming characters.
Dim i As Long
Dim sBuff As String ' buffer for holding incoming characters
Const MTC As String = vbCrLf ' message terminator characters (ususally vbCrLf)
Const LenMTC As Long = 2 ' number of terminator characters, must match MTC
Dim iPtr As Long ' pointer to terminatior character
' OnComm fires for multiple Events
' so get the Event ID & process
Select Case MSComm1.CommEvent
' Received RThreshold # of chars, in our case 1.
Case comEvReceive
' read all of the characters from the input buffer
' StrConv() is required when using MSComm in binary mode,
' if you set MSComm1.InputMode = comInputModeText, it's not required
'sBuff = sBuff & StrConv(MSComm1.Input, vbUnicode)
'If Len(txtMessage.Text) > 4096 Then txtMessage.Text = ""
sBuff = MSComm1.Input
Dim ch As String
Dim PacketStart As Boolean
Dim PacketLength As Integer
Dim Packet() As String
PacketStart = False
PacketLength = 0
While (Len(sBuff) > 0)
ch = Left(sBuff, 1)
If (ch = Chr(&HAA)) Then PacketStart = True
If (ch = Chr(&HBB)) Then PacketStart = False
If (ch <> Chr(&HAA) And ch <> Chr(&HBB)) Then
PacketLength = PacketLength + 1
ReDim Preserve Packet(PacketLength)
Packet(PacketLength) = ch
End If
'txtMessage.Text = txtMessage.Text + Format(Hex(Asc(ch)), " @@")
sBuff = Right(sBuff, Len(sBuff) - 1)
Wend
If (PacketLength = 3) Then
Debug.Print "Command packet recieved"
'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(1)))
'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(2)))
End If
If (PacketLength = 4) Then
Debug.Print "Response packet recieved"
txtMessage.Text = txtMessage.Text + "Address =" + Str(Asc(Packet(1))) + _
" Answer = " + Answers((Asc(Packet(2)) And &HC0) / 64) + _
" Time =" + Str((Asc(Packet(2)) And &H3F) * 256 + (Asc(Packet(3)))) + "mS" + vbCrLf
'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(1)))
'txtMessage.Text = txtMessage.Text + vbCrLf + "Option =" + Str((Asc(Packet(2)) And &HC0) / 64)
'txtMessage.Text = txtMessage.Text + vbCrLf + "Time =" + Str((Asc(Packet(2)) And &H3F) * 256 + (Asc(Packet(3))))
End If
If (PacketLength <> 4 And PacketLength <> 3) Then Debug.Print "Unknown packet of length" + Str(PacketLength) + " recieved"
txtMessage.Text = txtMessage.Text + vbCrLf
' An EOF charater was found in the input stream
Case comEvEOF
DoEvents
' There are SThreshold number of characters in the transmit buffer.
Case comEvSend
DoEvents
' A Break was received.
Case comEventBreak
DoEvents
' Framing Error
Case comEventFrame
DoEvents
' Data Lost.
Case comEventOverrun
DoEvents
' Receive buffer overflow.
Case comEventRxOver
DoEvents
' Parity Error.
Case comEventRxParity
DoEvents
' Transmit buffer full.
Case comEventTxFull
' Unexpected error retrieving DCB]
Case comEventDCB
DoEvents
End Select
End Sub
Private Sub tmrRead_Timer()
'MSComm1.Output = vbCrLf + vbCrLf
'MSComm1.Output = Chr(128)
End Sub
Private Sub txtMessage_KeyDown(KeyCode As Integer, Shift As Integer)
If Shift = 2 Or Shift = 4 Then RejectKeystroke = False Else RejectKeystroke = True
End Sub
Private Sub txtMessage_KeyPress(KeyAscii As Integer)
If RejectKeystroke Then
KeyAscii = 0
End If
End SubThanks in advance..I want to replicate the entire VB program as Java Program.
This has to be included in my project which i am doing in java. -
Writing bytes to serial port in each iteration of loop
Hello everyone,
Well I am new to labview, my question might of beginner's level but i have searched the forums and didnt find content regarding it. Kindly help me through it as i am really stuck in it for last three days.
I have to make a packet of bytes in each iteration depending upon the bytes i get from array which is input to for loop. Taking five bytes and then making packet according to protocol. Once packet is made i have to send it to serial port in the same iteration. So for each iteration i have to send packet to serial port. I have tried the shift registers, local variables, and also the autoindexing which returns the array at the end of loop. But these things dont solve my problem. Kindly help me solvng this issue.
Many many thanks in advance
Engr. Yasir AminFirst of all thanks alot for your reply.
The problem is that i have made separate subVI for this protocol stuffing and the output of that subVI is attatched to the serial visa write in another main VI in which i am using this VI. I have sent parameters to subVI which makes the packet and then send the output, the output is then sent to visa serial write. Actually that visa serial write is common to many subVIs, On the interface its user's choice to select the request he wants to send. The based on the request the particular subVI is chosen and then that subVI generates the string which is in main VI. which is written to serial port. All other subVis are working fine becoz they dont have loop they simply make the string and send it to port. But this subVi with the loop has the problem as it sends only the last iteration string to port.
I cant post the code as i am using my laptop in my room and the code is in office laptop But tomorrow i can share it from office
Thanks
Yasir -
Java program to receive byte from serial port
hello everyone, i am recently working one a project which require communication between pic16f877 and PC. My pic continuiously measure a voltage and send the result (a byte ranging from 0 to 255) to the rs232 port. One the pc side, my java program keep reading the serial port and it works for values 0~127 and 160~255. But if the byte value is between 127 and 160, it cannot received correctly, i get something like 375,8224,or even 65532 etc(no obvious path but more likely to be 300+,700+,8000+ or 65500+). I have been trying very hard to solve this and i think the problem is due to the pc software. I am feeling so frustrated and any suggestion will be much appreciated.
p.s. : i used Bufferedreader.read() in my program
--mengyaofumengyao wrote:
hello everyone, i am recently working one a project which require communication between pic16f877 and PC. My pic continuiously measure a voltage and send the result (a byte ranging from 0 to 255) to the rs232 port. One the pc side, my java program keep reading the serial port and it works for values 0~127 and 160~255. But if the byte value is between 127 and 160, it cannot received correctly, i get something like 375,8224,or even 65532 etc(no obvious path but more likely to be 300+,700+,8000+ or 65500+). I have been trying very hard to solve this and i think the problem is due to the pc software. I am feeling so frustrated and any suggestion will be much appreciated.
p.s. : i used Bufferedreader.read() in my program
--mengyaothis may not matter in your case - but don't use a Reader, use a Stream (BufferedInputStream maybe) -
VISA get resource name doesn't return USB serial ports
We built an application on a computer that had an onboard serial port - COM1. We put the option to change the COM port in the application. We installed the built application on a computer with no serial ports, but installed a USB to serial converter that registers as COM3. LabView does not see this port, even with a test application to return only the VISA resource names.
We have verified that the port is good with another program (a Modbus simulator) and installed the latest VISA runtime v4.41 separately to no avail.
Any suggestions at further troubleshooting would be extremely helpful.
Joe T.
Solved!
Go to Solution.My main application still isn't working, but now the small test ones are.
Here's what I did:
1. Update my LabView 8.5 with the latest VISA runtime - 4.4. This updated the Installer as well.
2. Added the MAX Installer to the build.
3. Added the NI-VISA Configuration Support to the build
4. Uninstalled the application and reinstalled it with the new install volume.
When I run MAX, COM3 shows up. It also shows up in the Get Resources test application. The simple test Modbus write program works, too. I have a sneaky feeling that COM1 may be hard-coded somewhere in the main application; our next task is to find where the communications breaks down in our code. The bottom line seems to be a lack of experience with the Application Builder on our part.
Thanks to all who contributed!
Joe T.
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