Disable/enable the serial port

Hello All,
I am using Labview to communicate with a Microchip PIC virtual serial port. Ocassionally the serial comms is lost. To recover the connection I open Device Manager then right click the faulty comm port then select disable ( a red cross appears on the icon). Next right click the port again and select enable. The port now communicates correctly again.
Is there a way to use System Exec to drive this behavior automatically once a fault occurs or some other method to drive DM using methods and properties?
Many Thanks
Chris
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Thanks for that, I am surprised at how simple it is to use DevCon however I still dont understand why cant I detect when the serial port fails.
Excellent workaround though

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Using a PS/2 keyboard on a Sparc workstation through the serial port

We have recently migrated an application that used to run on a PC, to now run on a Sparc Workstation. This is a SunBlade 1500, running Solaris 8. The application is running in a dedicated console which has a fitted keyboard and trackerball that have PS/2 connectors and cannot be changed.
We need a way of connecting the PS/2 keyboards to the serial ports of the Sparc workstation. We already have a piece of software that will read ascii values from the serial port so we definately want to go through the serial ports.
Can someone please suggest what converters will be required to get the output of the keyboard and trackerball as ascii input to the serial port.

Actually, that's not a bit perverse, at all.
Jonathan's suggestion is a standard method of connecting to a server.
(null cable between the computer serial ports)
... see the Solaris man pages.
man tip
TeraTerm and Hyperterminal are customarily used on a PC running some dialect of Windows.
The 'tip' command is all that's necessary between Solaris systems.
PS/2 is not a serial connection, but is a keyboard/mouse interface 'invented' by IBM when they offered their XT-class PS/2 line of desktop systems, back in the 1980's.
I found this next link by using Google:
http://members.chello.at/theodor.lauppert/computer/ps2/
The smaller DIN ports were more compact than the AT-class keyboard ports and the mouse moved from a serial port to a dedicated mouse port.
Serial communication devices are not keyboards, per se,
and keyboards are not serial communication devices.
You need other hardware in between to translate what the human being sends, and another computer is a common method to accomplish that translation.
Having said all that ...
Since you cannot change the dedicated console hardware,
I suggest you go to the manufacturer of that console equipment
and have them suggest some sort of serial-to-serial interface lash-up.

How to get a signal from the serial port to start a labview program?

I need to synchronize the data obtained from a program (which is not in Labview)with the data collected with Labview on a different computer. I can send some data strings to the serial port of the computer running the Labview program when the other program starts. However, I need to be able to read the trigger in my Labview program. Do you know what I should do? Thanks.

If you don't have any other programs listening on the COM port, you need to let a LV program run BEFORE the signal comes, otherwise you won't be able to read it. You can have the program wait in a slow timed loop so that it doesn't use up too much CPU time, and when the required "trigger" comes, to move into the main part of the program.
You basically need a while loop waiting for a certain string in the serial buffer. Once the string is found the while loop is exited, and the data acqquisition or whatever else you require from the progam can be performed.
In the example attached the program wait for ANY text to be sent to the COM port. Please note that you need to configure the VISA resource before using it. Once there is something at the COM port, the loop will exit and the rest of the program will be executed.
Hope this helps
Shane
Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)
Attachments:
Wait for serisl message.vi ‏17 KB

How can I use the output value from SIMPLE PID to write something to the serial port?

I am working on my Senior Design Project that requires the use of incoming compressed air, propotional valves, continuous servo motors, and a serial servo motor microcontroller. I have figured out how to send byte sequences to the microcontroller through LabVIEW using the VISA serial write function. The motors are attached to the valves to control the flow rate. I have created my own simple feedback system using a bunch of case structures but I realized that I am basically trying to recreate the wheel (I basically was writing my own PID VI). I have an older version of LabVIEW (7.0 Express) and theres no way to upgrade or buy the PID toolkit, so I am stuck using the Simple PID VI. Also, the only way the motor works is sending an array of bytes to tell it to turn on/off, direction, and speed. Is there any way I can use the Simple PID VI in conjunction with the VISA SERIAL write function, or is there any other way I can communicate with the serial port using this pid vi? Any information would be appreciated.

Hi gpatel,
you know how to communicate to serial port, but you don't know how to send a value from SimplePID to serial port???
You know how to communicate, but then you don't know how to communicate???
You should explain this in more detail...
Edit:
From you first post you know what values your motor driver is expecting. You know which values the PID.vi is providing. Now all you need is a formula to reshape the values from PID to the motor. It's up to you to make such a formula. Unless you provide any details we cannot give more precise answers...
Message Edited by GerdW on 02-28-2010 08:35 PM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Is it possible to choose the serial port if only the run time engine is installed

I have an application, which communicates over the serial port. When I use the full version of Labview I can change the serial port without any problem from Com1 to Com2 (similar to the example “Hardeware input output -> serial -> Labview serial vi"). When I build an application and try to run this program on a computer where only the run time engine 6.1 is installed, it is not possible to choose the serial port. Since there is no “Measurement and Automation Explorer” available on the run time engine and no directory C:\VXIpnp is created, when the run time engine is installed, I do not see a way, how I can satisfy the computer with the information it needs for configuring
the different ports. Any suggestions?

Hi Daniel,
Before LV6.1 there was LV5.1 In LV5.1 the way to Spedify a resource was to use a string control with correct VIsa Resource Class identifier. For eg. "GPIB0::11" or "ASRL1::INSTR". With Introduction of VISA Resource Name Control and linking with MAX, These names are Available from Pull Down List and Can be Aliased, meaning ASRL1 which is Serial Port 1 can be called COM1 and so on. However the old method still works with all 6.1 Controls. Only thing is you have to make sure you Dont Conflict the Class Names ie Use "GPIB::.." instead of "ASRL..." when addressing Serial Port VI's.
To solve your Problem I would Build a Menu ring with COM1 to COM4 in the Pull Down List.
Next, If I use the Traditonal Serial Port VI wich accepts the Integer as Seria
l Port #. I just Wire the Menu Ring to this VI.(Remember COM1 is 0, COM2 is 1 for this VI)
If I use VISA Config Serial Post. I build an Array Constant with Corresponding VISA Class Names So in our case a String Array Constant of 4 elements "ASRL1::INST" to "ASRL4::INST". I Use Index Array Function With the Index Wired to my Menu Ring. The Array Input Terminal Wired to the Array Constant. The Output of this Array will be correct Visa Class Name Based on slection of my Menu Ring. I can Wire this as Input to my VISA Config Serial Port Vi.
I have attached a Small VI to Illustrate this.
Drawback: You must Predefine what Ports you will Want to Use. Basically you define all the cases.
I hope this Answers your Q!
Good Luck
Mache
Good Luck!
Mache
Attachments:
Serial_Port_Select.vi ‏36 KB

How to use the serial port

hello
I would like to know if there is other library than comm to use to establish communication with the serial port ..
can we do this with pure java ,I mean without the need of using any library ???
if not then what is the best library to use ???
any examples ??
I have other question
when i use the library comm
I use the public void serialEvent(SerialPortEvent event) to get my data
but that data comme line by line
is there a way to get all the data at once ???
than kyou in advance

There you go
http://java.sun.com/products/javacomm/
Some extra resources
http://www.google.co.in/search?q=java+access+serial+po
rt&start=0&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.
mozilla:en-US:officialmaybe I was not clear ,I know the comm lib
Im already using it
but am asking if there any other lib that will work for windows
thank you

How to access the serial port in Java?

How can I initialise and access the serial port for writing and reading data from it? Are there any code examples available?

I tried that and I tried compiling and executing one of its examples, the one below:
import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleWrite {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString = "Hello, world!\n";
static SerialPort serialPort;
static OutputStream outputStream;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
if (portId.getName().equals("COM1")) {
//if (portId.getName().equals("/dev/term/a")) {
try {
serialPort = (SerialPort)
portId.open("SimpleWriteApp", 2000);
} catch (PortInUseException e) {}
try {
outputStream = serialPort.getOutputStream();
} catch (IOException e) {}
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
try {
outputStream.write(messageString.getBytes());
} catch (IOException e) {}
But when I execute this I get the error:
Exception in thread "main" java.lang.NoClassDefFoundError: SimpleWrite
What is wrong with this example??

I want to transfer data through the serial port in the same coding that hyperterminal uses. How can i do it?

The serial port seems to be working, and labview seems to be sending the data, but the problem is in which format does it send the data, because in hyperterminal i just input the string "JDX" and it sends it to my device, with labview it sends something but my device does not recognize it.

nobuto wrote:
> I want to transfer data through the serial port in the same coding
> that hyperterminal uses. How can i do it?
>
> The serial port seems to be working, and labview seems to be sending
> the data, but the problem is in which format does it send the data,
> because in hyperterminal i just input the string "JDX" and it sends it
> to my device, with labview it sends something but my device does not
> recognize it.
Hyperterminal adds the carriage return/line feed to the string which is
generated by the return key to send out the current line. LabVIEW simply
sends out what you tell it, so try to set the string to "Show \ Display"
format and add a \r or \n or \r\n to the command you want to send out.
Assumes of course that you set the right baudr
ate/bits/parity etc in
LabVIEW with the VISA property node, when opening the serial port.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

How can I use LabVIEW to send the equivalent of a CTRL D (in VT 100 format) out the serial port of my computer?

I am trying to write a vi that interfaces with a piece of OEM equipment that is set up to talk with a VT 100 terminal. I can't seem to locate the ASCII equivalent string (if there is such a thing) of a CTRL D. Is there a vi that emulates VT 100 commands?

If I recall, CTRL-D is EOF on most ASCII tables.
You'd probably have to use an escape sequence
or if you can use an unsigned 8-bit that might be
easier.
In article <[email protected]>, TLS
wrote:
> How can I use LabVIEW to send the equivalent of a CTRL D (in VT 100
> format) out the serial port of my computer?
>
> I am trying to write a vi that interfaces with a piece of OEM
> equipment that is set up to talk with a VT 100 terminal. I can't seem
> to locate the ASCII equivalent string (if there is such a thing) of a
> CTRL D. Is there a vi that emulates VT 100 commands?

Reading a whole frame from the serial port

I have posted before about my attempts to use the serial port (http://forums.ni.com/ni/board/message?board.id=170&thread.id=387410).
Anyway, I want to connect an external device through using VISA. It uses a protocol that exchanges frames. My main program is a series of while loops going through the different echanges, it sends one frame, waits for the proper response, sends the frame again etc.
My problem lies in reading the frames. I'd like to read from the serial port until I get an EOF character, then parse the frame, etc. for every cycle of send/check. This doesn't work. I've managed to get one character from the port, thereby confirming that my reading function does actually read. Then I tried to put it into a loop which resulted in it not returning any characters at all.
Attachments:
AssReq.GIF ‏5 KB
GetFrame.vi ‏14 KB
readVISA.vi ‏13 KB

Attachments:
SerialPortControl_2.vi ‏24 KB

How to unbundling binary structure coming through the serial port

Hi to all
I have a board that is transmitting a binary stream. This stream is a structure repeated constantly ... the payload of this structure looks like this
I have no problem reading the serial port and disaplying ASCII data but this is not my application.
ANALOG_COUNT is (2)
typedef struct
uint16_t light;
float TempAmbient;
float TempTarget;
uint16_t ADC[ANALOG_COUNT];
int16_t AccX;
int16_t AccY;
int16_t AccZ;
}StreamContext_t
The idea is for me to, once I get the 20 bytes that comprise the strcture I want to brake it into its elements to feed it to graphs or what ever.
Thanks
Alejandro
Solved!
Go to Solution.

You are still making life to difficult. Try this. It is much simpler to understand and it will work correctly. Ok, there may be some debugging.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
Attachments:
Start.vi ‏18 KB

I want to build an array using the data that I get through the serial port

I am reading data through the serial port, but I want to buffer these data. I have seen a function, but i think that i can use this if I am reading data from I/O intrument, so I don´t how can I fill an array, with the data that I am reading!!!
Thank you!!!

I'll hazard a guess that you are reading data with VISA as a string. Then you want to convert that (probably with Scan From String) into a number. Then, you want to collect those numbers into an array.
We don't really have enough information to tell you the best way to do this. Here are some ideas.
If you are reading all the numbers from the instrument at once (e.g., a waveform from a scope), you might consider using "Spreadsheet string to array". Most scopes return the data as ASCII with commas between the values, so you'd wire a "," to the "delimiter" input of the "Spreadsheet string to array" function.
If, however, the instrument is returning a single point at a time, there are more questions. Do you want to do this continuously, or do you want t
o collect only a certain number of data points, and then process them as a block?
If the latter, then you'd just acquire each data point, convert it to a number, and then use output indexing on the for loop to create your array.
If the former, then you may want to store the data in a queue, and read it from the queue elsewhere in your program.
If you let us know what you want to do, we can probably provide more precise help.
Brian

Why does a standalone program created in Labview 8.5 try connecting to the internet when the program only reads data through the serial port? Firewalls object to progams that contact the internet without permission.

why does a standalone program created in Labview 8.5 try connecting to the internet when the program only reads data through the serial port? Firewalls object to progams that contact the internet without permission.
The created program is not performing a command I have written when it tries to connect to the internet, it must be Labview that is doing it. How do I stop this from happening?
Any help would be very appreciated.

It looks that way..
"When LabVIEW starts it contacts the service
locator to removes all services for itself. This request is triggering
the firewall.This is done in case there were services that were not
unregistered the last time LabVIEW executed- for example from VIs that
didn't clean up after themselves"
This is not yet fixed in LV2009.
Message Edited by Ray.R on 11-04-2009 12:25 PM

Determining the Serial port number

I need to test my board on 3 PCs randomly.Each time i connect the board the serial port number like "com 18" is getting changed.Now the comport number i am using is 40.Though i dont any other USB connection.Though i refresh i still get the data only if i define the port number as 40.Is there anyway to determine the port number.Also can someone tell me why this is happening?
Solved!
Go to Solution.

I think you have USB 1.0, it will always take a new port number if you install a new one. (:unsure)
To find the right COM-Port of your device you can do following:
1) send anything on each port and wait a little for the right answer, if OK,than take this port for communication.
or 2) you can get the description string of all ports installed from the device manager. If your USB-Serial-converter have a unique description string, you cann compare all descriptions with your one, and if it conforms, thank take this port for communication.
LabVIEW Portal

How to retrieve data from the serial port and decode it each 2 bytes is a long variable and 1 frame is about 6 bytes

I send the frame by a microcontroller ( 8bits) the fram contains 6 bytes, 2bytes conform a long variable, I want to decode the frame and make operations with these long variables and then plot them

Hey jpvans,
I would first suggest using NI-VISA to talk to the serial port. Then, you can use the LabVIEW Type Cast or the Flatten to String and UnFlatten From String VIs to convert the data.
You can setup the read so that it reads just two characters at a time to form an individual long or you can set the read up to read it all and then use the string functions like String Subset to cut the information into chunks.
I hope this helps out.
JoshuaP

Disable/enable the serial port

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