Serial communication RS232

hi,
I have a requirement of allocating the available installed ports in my pc for vaious processes. For example if i have the following ports say com1 ,com2 and lpt1 in my pc, i should allocate the currently available ports alone. If i have allocated com1 for a particular task it should be disabled for other users until the task is finished and the com1 is released. How do i achieve this. Also if i try opening com1 thro visa configure it opens without any error even if com1 is already opened and is not closed. Whereas if i open com1 thro hyperterminal and try opening com1 again thro labview (visa configure) it gives me an error saying resource not available, it is used by other service. Why is this so? Can someone help me out in resolving this issue...
Thanks
Jay

Hi Jay,
you can lock and unlock the VISA resource. Use the VISA lock and VISA unlock function for it.
Mike

Similar Messages

I was unable to establish a serial communication using a DLL library file

i had designed a VI application in Labview7.1, now i had upgraded Labview to 8.5 but my application is not responding. The design includes
Application: I am trying to access a third party controller, through serial communication(RS232 Cable). I am configuring the serial port using a third party DLL library file using call library function block. but i cannot get the starting reciever response.

hi santosh,
                   i cant get u, How do i check whether the dll is activex dll or not. else i do have an activex dll. Mouse, keyboard are USB connected. no other serial communication is connected to it. I am geting 2 errors when i tried to register the file
                     1. DLL server point not found          --    sometimes
                     2. The module was not found        -- sometimes
              One more thing is i am able to get the reciever status for the first time but was unable to connect for the consequtive bit/byte loadings. to the third party controller connected at the other end.

Applet- RS232 serial communication

Hi,
Can any one tell how to do applet -RS232 serial communication?Do i signed applets? any secuirty policies to incorporated?
Thanx
/JP

you need to install the jre, and place the win32.dll at JavaSoft\JRE\1.3.1_06\bin, that properties file place at JavaSoft\JRE\1.3.1_06\lib, comm.jar at JavaSoft\JRE\1.3.1_06\lib\ext\
and in ur code try to use it to open ur com port
public String test() {
String drivername = "com.sun.comm.Win32Driver";
try
CommDriver driver = (CommDriver) Class.forName(drivername).newInstance(); driver.initialize();
catch (Throwable th)
{* Discard it */}
drivername = "javax.comm.*";
try
CommDriver driver = (CommDriver) Class.forName(drivername).newInstance(); driver.initialize();
catch (Throwable th)
{* Discard it */}
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
if (portId.getName().equals("COM2")) {
//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) {}
int i=0;
while(true)
try {
messageString="hi";
System.out.println(i++);
outputStream.write(messageString.getBytes());
} catch (IOException e)
System.out.println(e);
messageString=String.valueOf(e);
return messageString;
and yet u need to signed the applet
1. Compile the applet
2. Create a JAR file
3. Generate Keys
4. Sign the JAR file
5. Export the Public Key Certificate
6. Import the Certificate as a Trusted Certificate
7. Create the policy file
8. Run the applet
Susan
Susan bundles the applet executable in a JAR file, signs the JAR file, and exports the public key certificate.
1. Compile the Applet
In her working directory, Susan uses the javac command to compile the SignedAppletDemo.java class. The output from the javac command is the SignedAppletDemo.class.
javac SignedAppletDemo.java
2. Make a JAR File
Susan then makes the compiled SignedAppletDemo.class file into a JAR file. The -cvf option to the jar command creates a new archive (c), using verbose mode (v), and specifies the archive file name (f). The archive file name is SignedApplet.jar.
jar cvf SignedApplet.jar SignedAppletDemo.class
3. Generate Keys
Susan creates a keystore database named susanstore that has an entry for a newly generated public and private key pair with the public key in a certificate. A JAR file is signed with the private key of the creator of the JAR file and the signature is verified by the recipient of the JAR file with the public key in the pair. The certificate is a statement from the owner of the private key that the public key in the pair has a particular value so the person using the public key can be assured the public key is authentic. Public and private keys must already exist in the keystore database before jarsigner can be used to sign or verify the signature on a JAR file.
In her working directory, Susan creates a keystore database and generates the keys:
keytool -genkey -alias signFiles -keystore susanstore -keypass kpi135 -dname "cn=jones" -storepass ab987c
This keytool -genkey command invocation generates a key pair that is identified by the alias signFiles. Subsequent keytool command invocations use this alias and the key password (-keypass kpi135) to access the private key in the generated pair.
The generated key pair is stored in a keystore database called susanstore (-keystore susanstore) in the current directory, and accessed with the susanstore password (-storepass ab987c).
The -dname "cn=jones" option specifies an X.500 Distinguished Name with a commonName (cn) value. X.500 Distinguished Names identify entities for X.509 certificates.
You can view all keytool options and parameters by typing:
keytool -help
4. Sign the JAR File
JAR Signer is a command line tool for signing and verifying the signature on JAR files. In her working directory, Susan uses jarsigner to make a signed copy of the SignedApplet.jar file.
jarsigner -keystore susanstore -storepass ab987c -keypass kpi135 -signedjar SSignedApplet.jar SignedApplet.jar signFiles
The -storepass ab987c and -keystore susanstore options specify the keystore database and password where the private key for signing the JAR file is stored. The -keypass kpi135 option is the password to the private key, SSignedApplet.jar is the name of the signed JAR file, and signFiles is the alias to the private key. jarsigner extracts the certificate from the keystore whose entry is signFiles and attaches it to the generated signature of the signed JAR file.
5. Export the Public Key Certificate
The public key certificate is sent with the JAR file to the whoever is going to use the applet. That person uses the certificate to authenticate the signature on the JAR file. To send a certificate, you have to first export it.
The -storepass ab987c and -keystore susanstore options specify the keystore database and password where the private key for signing the JAR file is stored. The -keypass kpi135 option is the password to the private key, SSignedApplet.jar is the name of the signed JAR file, and signFiles is the alias to the private key. jarsigner extracts the certificate from the keystore whose entry is signFiles and attaches it to the generated signature of the signed JAR file.
5: Export the Public Key Certificate
The public key certificate is sent with the JAR file to the whoever is going to use the applet. That person uses the certificate to authenticate the signature on the JAR file. To send a certificate, you have to first export it.
In her working directory, Susan uses keytool to copy the certificate from susanstore to a file named SusanJones.cer as follows:
keytool -export -keystore susanstore -storepass ab987c -alias signFiles -file SusanJones.cer
Ray
Ray receives the JAR file from Susan, imports the certificate, creates a policy file granting the applet access, and runs the applet.
6. Import Certificate as a Trusted Certificate
Ray has received SSignedApplet.jar and SusanJones.cer from Susan. He puts them in his home directory. Ray must now create a keystore database (raystore) and import the certificate into it. Ray uses keytool in his home directory /home/ray to import the certificate:
keytool -import -alias susan -file SusanJones.cer -keystore raystore -storepass abcdefgh
7. Create the Policy File
The policy file grants the SSignedApplet.jar file signed by the alias susan permission to create newfile (and no other file) in the user's home directory.
Ray creates the policy file in his home directory using either policytool or an ASCII editor.
keystore "/home/ray/raystore";
// A sample policy file that lets a JavaTM program
// create newfile in user's home directory
// Satya N Dodda
grant SignedBy "susan"
permission java.security.AllPermission;
8. Run the Applet in Applet Viewer
Applet Viewer connects to the HTML documents and resources specified in the call to appletviewer, and displays the applet in its own window. To run the example, Ray copies the signed JAR file and HTML file to /home/aURL/public_html and invokes Applet viewer from his home directory as follows:
Html code :
</body>
</html>
<OBJECT classid="clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"
width="600" height="400" align="middle"
codebase="http://java.sun.com/products/plugin/1.3/jinstall-13-win32.cab#Version=1,3,1,2">
<PARAM NAME="code" VALUE="SignedAppletDemo.class">
<PARAM NAME="archive" VALUE="SSignedApplet.jar">
<PARAM NAME="type" VALUE="application/x-java-applet;version=1.3">
</OBJECT>
</body>
</html>
appletviewer -J-Djava.security.policy=Write.jp
http://aURL.com/SignedApplet.html
Note: Type everything on one line and put a space after Write.jp
The -J-Djava.security.policy=Write.jp option tells Applet Viewer to run the applet referenced in the SignedApplet.html file with the Write.jp policy file.
Note: The Policy file can be stored on a server and specified in the appletviewer invocation as a URL.
9. Run the Applet in Browser
Download JRE 1.3 from Javasoft
good luck! [email protected]
i already give u many tips, i use 2 weeks to try this to success, hopw that u understand that, a result of success is not important, the process of how to get things done is most usefull!

Serial Communication In JAVA

Hi.
I just wanted to know if serial communication is possible using java. If yes, which are the classes used.
Thank you.

I have found javax.comm for Linux and Solaris but not for Windows can any body help me about it .
How can I comunicate using rs232 two computers using Java in Windows.
Tkns
I

Serial communication in j2me

hi,
is serial communication via an rs232 port is possible in j2me to be used in micro devices?
thanx

Check the search engine top right
http://forum.java.sun.com/thread.jsp?forum=31&thread=50052

Serial devices RS232, OCX or PLL

I am looking for a FORMS pll or ocx to talk to serial devices (RS232). Is there an interface for Oracle to download?
null

You should be able to use almost any terminal emulation application, e.g. the shareware program ZTerm or the communications section of one of the ClarisWorks versions, to receive data/files directly in a Mac OS 8.6 environment.
In order to view image files, something like the shareware utility GraphicConverter may be of interest to you.
Jan

VISA bug with serial communication on MAC !

Hello to you all again,
I have appreciated all feed back from you about a problem encountered with serial communication on the MAC (see earlier questions)
To situate the problem:
One can only read 63 bytes back from the serial port using VISA calls (without handshaking). With the old serial VIs you can read everything back. In addition the exact same VIs do not show this problem on windows platform.
I have now performed extensive tests with a loopback on the serial port and the problem still stand.
I attach two VIs to an answer to this question (for some obscure reason I can not attach them to the question?) which do the basic loopback, one uses VISA the other the old serial VIs. Please try them out o
n your computer (for Mac RS422 miniDIN you should connect pin 3 to 5 and 6 to 8 to do the loopback)(for windows RS232 DB9 connect pin 2 to 3) in loopback configuration (see also resource library).
Please post a message if the described problem also occurs on your MAC.
Thanks to all of you for your cooperation!!

here are the VIs a promised
Attachments:
serial_loopback_test.vi ‏65 KB
visa_loopback_test.vi ‏70 KB

Handling multichannel serial communication on FPGA

NI recently released cRIO modules for serial communication on RS232 and RS485/422. We need multiple RS232 channels for our RIO systems and previously the solution would have been to use a serial port server and then communicate with that using raw TCP/IP. Having the serial communication handled by RIO modules seems a bit more elegant though so I'm looking into using the RS232 module NI9870 instead.
NI has supplied an example on how to use the 9870 - a serial loopback on port 0. I've successfully modified this to be a general driver for a selectable port (added port selection and initialization), however I really need to code a solution that handles ALL the 4 channels in parallell. I'm not sure what would be the best way to do that though. DMA FIFOs seem to be the best option for host-target communication, however in this case there are 4 channels....and I may have multiple modules so at most it could be that I need to handle as much as 32 ports. The example uses interrupts for synchronization....which off course is also a limited resource. All in all I'll probably figure out a way to do this, however if anyone else have done something similar already it would be great to hear your views on this.
Coming from the Windows-programming world (this is the first FPGA work I've done) I was also hoping to make this driver as general as possible, maybe even be able to write a wrapper containing both VISA based serial functions and the FPGA host code. That way it could be transparent how the port is accessed.
This would require 1 code that would be able to handle a variety of module configurations (well, 1 to 8 NI9870 modules in the chassis), however that does not seem to be feasible(?). When you read or write to a port you cannot just refer loosely to it with a number e.g. - the read and writes are referenced to a specific port...this means that unlike in a Windows application where you can let the user just configure that he wants to use COM port num XX and the serial functions will accept that number regardless of whether the port exists or not (returning an error if it does not exist or is in use) - the FPGA code has to have all the items it will call pre-defined. If the chassis can have 16 ports on 4 9870 modules it does not seem possible to use the same FPGA code if the chassis currently only has 1 module...Is this the reality, or is it possible to create a more flexible solution?
If it turns out that the FPGA has to be reprogrammed if another serial module is added (or one is removed) it would seem much better to drop the modules and use a port server and tcp/ip instead...that way using new ports will only be a question of configuration (IP and port), not reprogramming...That may not be possible always (if you need the compact size and roughness only a single RIO chassis would offer), but in our case it is - it' just not as elegant hardware-wise.
MTO

Well, the multichannel experiment only wrote data, it did not read...(see attached VIs) however the concept can be used in both directions: Add a header to the FIFO data where the header tells the recipient what port the data is going to or comes from...Then use e.g. a state machine to read the FIFO, split the header and data, and route the data to the loop handling the port.
If you are going to read data you will get into one of the downsides to this namely that you will need to have a central communications manager that reads the incoming data and distributes it to the requesting VI. This way you can have more parallell access to both read and write, however the reads will have to be routed through this handler. How big a performance gain this would give is unknown though. You still only have one DMA FIFO for each direction so there is a limit to how parallell things can get, but logically this might get you closer than the NI example...
MTO
Attachments:
9870 MultichannelIO Experiment.zip ‏1002 KB

How to send data using serial Communication

I want to make serial communication using RXTXcomm.jar file.I was written the code.From this I got the list of serial ports avilable on pc but then after when I was tring to send command to machine which is attached to port it didn't gave any reply.
Tell me that how to send command to port?

This is how I do it:// open port, get ownership
SerialPort serialPort= (SerialPort)portId.open(APPLICATIONNAME, timeout);
// no framing and no threshold
serialPort.disableReceiveFraming();
serialPort.disableReceiveThreshold();
// communication speed, parity, stopbits and databits
serialPort.setSerialPortParams(BAUDRATE, SerialPort.DATABITS_8,
SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
// no handshaking or other flow control
serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_NONE);
// timer on any read of the serial port
serialPort.enableReceiveTimeout(TIMEOUT);
// open streams for reading and writing
InputStream is= serialPort.getInputStream();
OutputStream os= serialPort.getOutputStream();... then you use the 'os' stream for writing and the 'is' stream for reading.
kind regards,
Jos

How do i open a new window? serial communication problem

I am trying to make a serial communication interface, with changeable settings,
but i wanted it to be that the settings to be openend in a new window, how am i able to do that.
I tried to make a separate subvi, but unable to do that, here is my explanation in images and the vi files.
-Just a student-
Attachments:
LVTerm.vi ‏50 KB

Hello Nandha,
SubVI's can be created by selecting the part that you want in the subVI and than select "create subVI" from the "Edit" menu.
Or cut the selected part and open a new VI and paste in the code. Then you have to connect all the controls and indicators to your connector pane. To do this right click the icon in the upper right corner and "Show connector". Select a pattern that has enough connectors, my personal favorite is the 4x4x4. Select the wire tool and select a connector and then the control or indicator you want to connect. Try to keep controls to the left and indicator to the right.
Now you have to figure out when you want to show the settings window. Is it necessary that the communication goes on during manipulation of the settings?
Kind regards,
André
Regards,
André
Using whatever version of LV the customer requires. (LV5.1-LV2012) (www.carya.nl)

Changing the name of serial communication example in lab windows. Urgent help required

I am using the example of getting data from rs 232 in lab windows. I want to use this in my final year project that's why I want to change its name that appears as "serial communication example" how can I change its name and how can I make its exe file that will run on any system even without lab windows.
How can I modify this example to save the data. I am very new to lab windows, I was using hyper terminal previously.

I am not informed about the file format that hyperterminal uses. However, CVI allows wiring to files. To get a list of functions that deal with file handling, press <Ctrl-Shift-p> to get the "Find Function Panel" dialog. Type in "file" and press the "Find" button. This will open a list of funtions that contain "file" in their name.

Problem download: Java serial communication

Hi,
I need to work with Java serial communication api for Windows.
As mentioned on SUN site, downloaded the following:
1) comm2.0.3.zip, &
2) rxtx-2.0-7pre1-i386-pc-mingw32.zip
Extracting, unable to see win32com.dll & javax.comm.properties
Can you help me?
Thanks,
Priya

Hi priya
There is problem in your downloaded s/w
Download commAPI once again then try
Read the readme file and follow the instruction

VISA Read function Read buffer problem in serial communication

Hi, I use VISA write and read function in serial communication app, the device continuously sends 0x00 if it is not receive a request from Labview program running on PC.
And the request sent by labview is programmable. I met a weird problem, each time the request changes, the VISA read buffer output port still shows the last request firstly, from second time, shows the right request.
It works like: Req code: ... 50, 51,51,51,50....; VISA Read buffer: ...50, 50, 51, 51, 51, 51, 50....
Please refer to the program.
Attachments:
readOne_test.vi ‏21 KB

How are you running this? You don't have a while loop around it. Is it part of a larger VI? Please don't tell me you are using the run continuously button.
You don't have any wait statement between you VISA Write and your bytes at port. So it is very likely the receive buffer is still empty since you didn't give your VI time to wait for the device to turn around and give a reply. If you read 0 bytes, your VISA read string will be empty. How does your decoder subVI (which you didn't include) handle an empty string?

To read 512 bytes using serial communication

I want to read 512 bytes of data using rs 232 with the timeout of 30ms. I am using "Serial read with timeout -Palm.vi". Is there a limitation of the number of bytes I can specify to this VI?
Thanks!!
Attachments:
Serial_Read_with_Timeout--Palm.vi ‏63 KB

Hi software enigineer,
It is not possible to transfer 512 bytes per 30 ms here. To do this would require a baud rate of 136533 (512*8/.03) and the maximum possible baud rate is 115000. The recommend baud rate for a serial transfer is 9600, which would mean transferring at most 36 bytes if the timeout is kept at 30ms. Moreover, there is usually some overhead involved in serial communication, and I would recommend sending a little less than the maximum 36 bytes every time too.
On another note, I noticed that in your block diagram, you are using the Bytes at Serial Port vi. Definitely use the output of this vi to determine how many bytes to read at a time and read the bytes as they become available in the serial buffer rather than reading in a large buffer
all at once. Continuously read and append the output until there are no more bytes to be read or until the termination character is read. This will avoid any lost data transmission due to overflow.
Good luck with your program!
Kileen Cheng
Applications Engineer
National Instruments

User-specified DAQ interruptions, instrument control through serial communication

I'm working on an instrument control program, and I've run into a structural problem that I cannot figure out.
The instrument in question is effectively a thermostat.
The program has two functions:
1.) Background sampling to record temperature in a log over time.
2.) Adjust temperature according to user input
The issue is that the instrument uses EIA-232 serial communication to talk to the PC.
This prohibits simultaneous execution. Attempting to send a command while the program is taking a sample will result in serial blockage errors.
So the program must interrupt background sampling until the specified command has been completed.
I can't figure out how to do this.
My best idea was to create a manual pause control. If the user wants to adjust the temperature, he hits a switch to pause the sampling, sends the appropriate command, then hits the switch again to reinitiate sampling. This method will suffice, but is not ideal.
Beyond that, I really have no idea how to prevent the two functions from running into each other.
Help structuring this program would be greatly appreciated,
Thank you

Look into Semaphores (icons with traffic light glyphs)
Set up a Semaphore resource to the COM port that is wired to two parallel structures.
One structure would do the background polling, the other would handle setting changes.
Prior to background poll, lock the resource, then unlock it after the poll. Likewise for the setting change command.
When a resource is locked, the other process cannot access it until it is unlocked. Be sure to dispose of the Semaphore when ending the program.
-AK2DM
~~~~~~~~~~~~~~~~~~~~~~~~~~
"It’s the questions that drive us.”
~~~~~~~~~~~~~~~~~~~~~~~~~~
Attachments:
SempahoreExample.jpg ‏256 KB

Serial communication RS232

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