Writing to serial port

I currently send ASCII characters to a serial port. I have not errors reported back. Everything appears to be error free, except that the device that I am trying to control does nothing. The device being controlled does not send anything back to the pc. The connection is strictly a one way connection. Do you have to send a carriage return or something to get the ASCII characters to "push" out of the buffer? - Sorry I don't have access to my code at the moment.

A portion of my code is below. What does the 'flush'
do? I thought it just emptied out the buffer.
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier)
tIdentifier) portList.nextElement();
if (portId.getPortType() ==
ortType() == CommPortIdentifier.PORT_SERIAL) {
if (portId.getName().equals("COM1"))
.equals("COM1")) {
try {
serialPort = (SerialPort)
portId.open("SimpleWriteApp",
d.open("SimpleWriteApp", 2000);
} catch (PortInUseException e)
ortInUseException e) {}People get life for this crime!
try {
outputStream =
outputStream =
tStream = serialPort.getOutputStream();
} catch (IOException e) {}So you now have two life sentences to serve.
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch
} catch
} catch (UnsupportedCommOperationException e) {}Sorry, three life sentences to serve.
try {
outputStream.write(rightString.getBytes());
} catch (IOException e) {}You get the prize! Four life sentences from a short bit of code.
}P.S. You should really use the COMM api for writing to serial ports.

Similar Messages

Writing to serial port 1 from a PDA

ok this program is driving me NUTS! i have this microchip which uses a certain protocol... now this protocol requires that you send it some characters in hexadecimal so it'll reset... afterwhich it'll send you a data packet containing the version of the microchip etc etc (it's an aduc812... which you can find on www.analog.com)... anyway, that's not important... i am having trouble actually WRITING to serial port 1... i noticed that doing it through an actual PC requires some sort of "open serial port.vi" which is not available in the pda version... all i have is init.vi which is apparently not enough from what i am told... i thas to be opened first... initialized next... then written to then read from... does anyone know how i can acc
omplish this open procedure with the pda module? is that some sort of software i'm missing? why isn't it included with the pda module add on... etc etc... thank you in advance... i really need help with this so as much information as possible would be appreciated... let me know if you need further info...
christina

Hey Christina,
Here is a link to a knowledge base one simply writing to the serial port from a PDA.
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=E011F478861443EFE034080020E74861&p_node=%20DZ52363&p_source=External
Hope this helps.
Brett

After writing into serial port, the same message gets bounced back into the Inqueue also. If anyone know how to avoid this, please rpely.

Hi,
After writing into serial port, the same message gets bounced back into the Inqueue also. If anyone know how to avoid this, please reply.
Thanks,
Ganesh

If you disconnect the cable going to the serial device, do you still get the echo? If so you have something going on in the port setup. If disconnecting the cable stops the echo then the device you're talking to is doing it - which would be my bet. One thing to check is whether this might not be normal operation. I have seen devices that if a command was successful, it simply echo'd back the command string you had sent. Also many serial devices have setting for specifying whether they are to echo commands.
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Reading/writing to serial port w/ VISA in Labview

I'm writing a Labview program to control and to read data from a Varian vacuum pump controller. It is connected to the serial port in my computer, and I have been trying to open a VISA session to communicate with the instrument. So far, however, the computer cannot see the instrument--I get the same error messages reading and writing to the instrument as I do to an empty serial port. Does anyone have any suggestions on what the problem might be? Thank you.

There are a lot of possiblities. Is the cable correct? You probably need a crossover cable (TX and RX) swapped. You also need to check and make sure the serial ports on both ends are set the same (i.e. baud rate, handshaking, stop bits, etc.). Make sure that the port is enabled. I've seen people try to use a comm port only to find that a modem card installation caused the port to be disabled. You could also try using hyperterminal to talk to the instrument. If you can communicate there, you can eliminate any hardware problem.

Problem writing to serial port

Hi All,
I am very new to LabVIEW (just a couple of months). I need to communicate with a serial port of an Advanced Energy RF generator (Ovation) serial port (AE Bus)
The manual talks about little endian conversion, CSR and checksum that I just can't make it work. does anybody know how to write and read to this serial port?
I have used the write and read to serial port from examples with no luck and no response from the generator. I have attached the generator's manual here, the serial commands section starts at page 65 (4-25)
Has anybody written a program to talk to Ovation RF generator? can anybody help me out and get me started? I am stuck!!!. ... appreciate your help. thanks.
~Johnny
~ Johnny
Attachments:
Ovation - AE RF generator.pdf ‏1444 KB

Thanks... so I started with the basic serial write and read, enetered hex text strings into the serial write, including the checksum and what I read back is not always correct because for example I need to calculate the XOR in the program and not just eneter it as a hex value. I should also put the write and read into a loop because I will be writing and reading to serial port 2 dozen times.
I am working with two devices, one is the generator, the other is a controller board that has a very similar serial bus structure as the generator's AE serial bus. the controller board has stepper motor drivers that move two variable capacitors. for the generator, I need to turn the power on and off and set to different power levels. for the control/stepper motor driver board: I need to read the values from a text file(attached). the text file has 3 table, table1, column1 is the number of steps that the stepper motor will move and column2 is the nominal capacitor values for C1. same thing table2; values are number of steps versus nominal cap values for C2. I need to creat a matrix such that to move the C1 to steps listed in the table, and for every step increment in C1, I need to move the C2 motor to 20 different position (listed in the table3 that has the desired percent value of total capacitance ) position and make a measurement of the impedance of the capacitors with agilant E5061 network analyzer and write the data back into the same text file at the end where it says "IMPEDANCE_REAL in Ohm one line per C1 position" and into a excel sheet too while taking a measurement... and do the same thing all over again for C2 versus C1. I think I need to use the producer consumer design pattern eventually when I get the details worked out first.
any suggestion? .... much thanks.
~ Johnny
~ Johnny
Attachments:
Basic Serial Write and Read1.vi ‏24 KB
cap-table.txt ‏7 KB

Error while reading/writing to serial port

Hello,
I am trying to read/write to my serial port but
this message shows every time i launch the
program. Does anyone know some help ?
Thanks
FdB
Attachments:
error2.ppt ‏172 KB

Frederico
This VI (LV8)
1. Open the serial port at 2400 baud
2. Powers down the PT104 and wait 0.5 secs for this to settle
3. Flushes the serial power buffer to remove any power down acknowledgements in the serial buffer
4. Powers up the PT104 waits 1 sec for things to settle
5. Reads any bytes in serial rx buffer.
6. Power down the PT104
7. Close the COM Port.
This is a bit of a guess but this is how I would approach it. Can you try this and let us know how you get on?
thanks
David
Message Edited by David Crawford on 07-20-2006 10:31 AM
Attachments:
PT104 - Get Version at Power Up.vi ‏56 KB
PT104 - Get Version at Power Up.jpg ‏50 KB

Reading and Writing For Serial Port (RS232)

Hi there;
I want to send data from my comport to a device and take data from there. I use Windows operating system. I looked at a bit javax.comm and RxTx.
Firstly do i have to use RxTx for my project because of i am using Windows operating system?And;
Where should i began to start simply send and receive data via RS232?
Edited by: furkankamaci on Feb 14, 2009 8:05 AM

Use RxTx and follow its examples.

Problems with access to serial port using reentrant code

Hi,
I have a VI that send commands and receive answers from an instrument using
de serial port.
This VI runs perfectly when used alone.
However I'm trying run two instances of that VI simultaneously using
reentrant code and I'm facing some problems.
Sometimes everything is OK but sometimes, in the process of writing to
serial port the following error happen:
Error code 36.
Invalid refnum device.
What is this?
Does someone know how to prevent this?
Thanks in advance for any help.

"Paro, Paula [CMPS:2721:EXCH]" wrote:
>
> Hi,
>
> I have a VI that send commands and receive answers from an instrument using
> de serial port.
> This VI runs perfectly when used alone.
> However I'm trying run two instances of that VI simultaneously using
> reentrant code and I'm facing some problems.
> Sometimes everything is OK but sometimes, in the process of writing to
> serial port the following error happen:
> Error code 36.
> Invalid refnum device.
>
> What is this?
> Does someone know how to prevent this?
>
> Thanks in advance for any help.
You can't use reentrant vi's vith serial vi calls without supervising of
driver.
Use VISA instead and you have to control the VISA session opening and
closing. Another word is that the only one serial port sess
ion should be
opened at a time.
Reentrant vi's for serial port without checking serial port session is a
mistake of program algorithm. Change it in any convenient way.
Sergey Krasnishov
Automated Control Systems
National Instruments Alliance Member
Moscow, Russia
[email protected]
http://acs.levsha.ru

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 Amin

First 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

Serial port writing return different in MAX and Labview

Dear all,
I have a very strange problem here. I had a device connected to the serial port, which can be started by sending "start\n".
Firstly, I used the IO in MAX to send "start\n", like the first figure, and the device operated correctly.
Then, I initialized the device, and used the program in the second figure, to write the same "start\n", but this time the device operated wrong.
I think the serial port setting are the same, and the device is not failed (after the second step, I repeated using MAX and still it's OK).
Could anyone to check what's wrong here?
Many thanks!

In your LabVIEW code, how do you know that it did not work?
Did you receive and error on the error indicator? You don't have any VISA Read going on, so you aren't trying to read the response.

Writing/reading from serial port

I need to write/read data from an instrument trough the serial port, the communication with the RS 232 cable works properly with hyperterminal, but failed with all the vi I tried for serial communication.I'm currently using RS 232 RT with write to file vi, I've checked the initialization is the same, if I write 1500(a space)NS, I then read 150 S S undefined, it looks like if some character are not read or there is a trouble to understand the code for the space. I've tried 4500(double space)NS(space) and it works but understand 450 NS, but to obtain 1450 NS I wrote 14500(double space)NS(space) and the trick didn't work. I don't get where the misunderstanding comes from ???
Thanks
Sand

I'm using a vi named "RS 232 RT with write to file" downloaded from your website. This vi uses the serial port write.vi and a carriage return is added at the end of the command. the instrument's syntax is a number follow by a space and NS, NS indicates the unit of the number.
Attachments:
RS232_RT_with_write__to_file.vi ‏256 KB

Writing double and unsigned integer to serial port

Hi all
I have a basic question. I am trying to write a double or unsigned intger to serial port. Is it possible to do so? If it is he case, how do I do it?
Thank you very much.
Best
Hideya

Hideya,
The serial port sends one text character at a time. So you must convert your numeric value to a text or string representation and then send the string.
LabVIEW has several functions on the String palette for numeric conversions. You must decide how to represent the number as text, floating point or exponential notation, number of significant digits, and other formatting issues. These may be dependent on what will be done with the data after being sent.
Lynn

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 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

Java ME 8 Permission check failed when opening a serial port

I have a larger Jave ME8.1 application that was going well until I tried to add one last piece, reading and writing data from a serial port. This was left to last because it is trivial, at least in most programming languages. The is IDE NetBeans 8.0.2 running on a Windows 7 PC. The platform is a Raspberry Pi B or B+ (I have tried both) with the most current Raspbian (12/24/2014 I believe). To simplify the process I created a new app with just the open and close code and this generates the same error I am experiencing in the larger application. The program is as follows:
package javamecomapp;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.microedition.io.CommConnection;
import javax.microedition.io.Connector;
import javax.microedition.midlet.MIDlet;
* @author ****
public class JavaMEcomApp extends MIDlet {
    static int BAUD_RATE = 38400;
    static String SERIAL_DEVICE = "ttyAMA0";
    static CommConnection commConnection = null;
    static OutputStream os = null;
    static InputStream is = null;
    static String connectorString;
    private int rtnValue = -1;
    @Override
    public void startApp() {
        java.lang.System.out.println("Opening comm port.");
        try {
            rtnValue = JavaMEcomApp.openComm();
        } catch (IOException ex) {
            Logger.getLogger(JavaMEcomApp.class.getName()).log(Level.SEVERE, null, ex);
    @Override
    public void destroyApp(boolean unconditional) {
        java.lang.System.out.println("Closing comm port.");
        try {
            rtnValue = JavaMEcomApp.closeComm();
        } catch (IOException ex) {
            Logger.getLogger(JavaMEcomApp.class.getName()).log(Level.SEVERE, null, ex);
        private static int openComm()throws IOException {
            java.lang.System.out.println("Opening comm port.");
            connectorString = "comm:" + SERIAL_DEVICE + ";baudrate=" + BAUD_RATE;
            commConnection = (CommConnection)Connector.open(connectorString);
            is = commConnection.openInputStream();
            os = commConnection.openOutputStream();
        return 0;
    private static int closeComm()throws IOException {
        java.lang.System.out.println("Closing comm port.");
            is.close();
            os.close();
            commConnection.close();
        return 0;
If I comment out the JavaMEcomApp.openComm and closeComm lines it runs fine. When they are included, the following error is dumped to the Raspberry Pi terminal:
Opening comm port.
Opening comm port.
[CRITICAL] [SECURITY] iso=2:Permission check failed: javax.microedition.io.CommProtocolPermission "comm:ttyAMA0;baudrate=38400" ""
TRACE: <at java.security.AccessControlException: >, startApp threw an Exception
java.security.AccessControlException:
- com/oracle/meep/security/AccessControllerInternal.checkPermission(), bci=118
- java/security/AccessController.checkPermission(), bci=1
- com/sun/midp/io/j2me/comm/Protocol.checkForPermission(), bci=16
- com/sun/midp/io/j2me/comm/Protocol.openPrim(), bci=31
- javax/microedition/io/Connector.open(), bci=77
- javax/microedition/io/Connector.open(), bci=6
- javax/microedition/io/Connector.open(), bci=3
- javamecomapp/JavaMEcomApp.openComm(), bci=46
- javamecomapp/JavaMEcomApp.startApp(), bci=9
- javax/microedition/midlet/MIDletTunnelImpl.callStartApp(), bci=1
- com/sun/midp/midlet/MIDletPeer.startApp(), bci=5
- com/sun/midp/midlet/MIDletStateHandler.startSuite(), bci=246
- com/sun/midp/main/AbstractMIDletSuiteLoader.startSuite(), bci=38
- com/sun/midp/main/CldcMIDletSuiteLoader.startSuite(), bci=5
- com/sun/midp/main/AbstractMIDletSuiteLoader.runMIDletSuite(), bci=130
- com/sun/midp/main/AppIsolateMIDletSuiteLoader.main(), bci=26
java.security.AccessControlException:
- com/oracle/meep/security/AccessControllerInternal.checkPermission(), bci=118
- java/security/AccessController.checkPermission(), bci=1
- com/sun/midp/io/j2me/comm/Protocol.checkForPermission(), bci=16
- com/sun/midp/io/j2me/comm/Protocol.openPrim(), bci=31
- javax/microedition/io/Connector.open(), bci=77
- javax/microedition/io/Connector.open(), bci=6
- javax/microedition/io/Connector.open(), bci=3
- javamecomapp/JavaMEcomApp.openComm(), bci=46
- javamecomapp/JavaMEcomApp.startApp(), bci=9
- javax/microedition/midlet/MIDletTunnelImpl.callStartApp(), bci=1
- com/sun/midp/midlet/MIDletPeer.startApp(), bci=5
- com/sun/midp/midlet/MIDletStateHandler.startSuite(), bci=246
- com/sun/midp/main/AbstractMIDletSuiteLoader.startSuite(), bci=38
- com/sun/midp/main/CldcMIDletSuiteLoader.startSuite(), bci=5
- com/sun/midp/main/AbstractMIDletSuiteLoader.runMIDletSuite(), bci=130
- com/sun/midp/main/AppIsolateMIDletSuiteLoader.main(), bci=26
Closing comm port.
Closing comm port.
TRACE: <at java.lang.NullPointerException>, destroyApp threw an Exception
java.lang.NullPointerException
- javamecomapp/JavaMEcomApp.closeComm(), bci=11
- javamecomapp/JavaMEcomApp.destroyApp(), bci=9
- javax/microedition/midlet/MIDletTunnelImpl.callDestroyApp(), bci=2
- com/sun/midp/midlet/MIDletPeer.destroyApp(), bci=6
- com/sun/midp/midlet/MIDletStateHandler.startSuite(), bci=376
- com/sun/midp/main/AbstractMIDletSuiteLoader.startSuite(), bci=38
- com/sun/midp/main/CldcMIDletSuiteLoader.startSuite(), bci=5
- com/sun/midp/main/AbstractMIDletSuiteLoader.runMIDletSuite(), bci=130
- com/sun/midp/main/AppIsolateMIDletSuiteLoader.main(), bci=26
java.lang.NullPointerException
- javamecomapp/JavaMEcomApp.closeComm(), bci=11
- javamecomapp/JavaMEcomApp.destroyApp(), bci=9
- javax/microedition/midlet/MIDletTunnelImpl.callDestroyApp(), bci=2
- com/sun/midp/midlet/MIDletPeer.destroyApp(), bci=6
- com/sun/midp/midlet/MIDletStateHandler.startSuite(), bci=376
- com/sun/midp/main/AbstractMIDletSuiteLoader.startSuite(), bci=38
- com/sun/midp/main/CldcMIDletSuiteLoader.startSuite(), bci=5
- com/sun/midp/main/AbstractMIDletSuiteLoader.runMIDletSuite(), bci=130
com/sun/midp/main/AppIsolateMIDletSuiteLoader.main(), bci=26
I have tried this with three different serial ports, /dev/ttyAMA0 (yes I did disable the OS from using it), an arduino board /dev/ttyACM0, and a USB to RS485 adaptor /dev/ttyUSB0. All of these ports could be connected and use normally with both a C program and terminal program in the Pi. The API Permissions were set in the project properties / Application Descriptor / API Permissions to jdk.dio.DeviceMgmtPermission "/dev/ttyAMA0". This of course was changed as I tested different devices.
I found a reference suggesting adding the line "authentication.provider = com.oracle.meep.security.NullAuthenticationProvider" to the end of the jwc_properties.ini file. This had no effect. I found references that during development in eclipse and NetBeans, the app is already elevated to the top level so this should not be an issue until deployment. This does not appear to be the case.
I am out of time and need a solution quickly. Any suggestions are welcome.

Terrence,
   Thank you for responding and confirming the issues I'm having with static addressing. As far as the example above, I do have the standard LEDs working correctly, however, the example I'm referring to above is from the JavaME samples using the GPIO Port for the LEDS, according to the Device I/O Preconfigured List you referenced:
GPIO Ports
The following GPIO ports are preconfigured.
Devicel ID
Device Name
Mapped
Configuration
8
LEDS
PTB22
PTE26
PTB21
direction = 1 (Output only)
initValue = 0
GPIOPins:
controllerNumber = 1
pinNumber = 22
mode = 4 (Push-pull mode)
controllerNumber = 4
pinNumber = 26
mode = 4 (Push-pull mode)
controllerNumber = 1
pinNumber = 21
mode = 4 (Push-pull mode)
So is the assumption that using GPIOPort for accessing the GPIO port for Device ID 8 as listed in the Device I/O Preconfigured list not supported?

Writing to serial port

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