RS422 on RPI

I need to send data to a device that talks RS422 from the RPI. My plan would be to use a USB to RS422 adapter. I am programing in Java ME. I am new to the RPI and Java ME and have never used serial ports on a linux OS. Could anyone give me some suggestion on how to proceed. Example code would be greatly apprieciated.

Hi!
I'm pretty sure your converter represents itself as standart serial port. Therefore you can open it as UART device without any side effect.
/Sergey

Similar Messages

Java 8 SE Embedded download - which version for my RPi?

One thing I struggle with is knowing which download for my RPi.
I keep reading I should use the hard floating point version. That said, here's the only Java 8 SE Embedded version I see with HardFP: ARMv7 Linux - VFP, HardFP ABI, Little Endian1
On my RPi, here's the output from "uname -a"
> Linux bsrpi 3.10.34+ #661 PREEMPT Thu Mar 27 00:36:02 GMT 2014 armv6l GNU/Linux
Will the HardFP version on the download page work on my RPi? It appears to be arm6.
The only thing I see available with ARMv6 is: ARMv6/7 Linux - VFP, SoftFP ABI, Little Endian2
If you have the answer or even refer me to a good site that explains the differences, I'd be very grateful. If not, I'll just keep pulling out my hair! :-)
Thanks for any help you have,
Brent Stains

I received help from Stephen Chin on this! Thank you Steve. You can see his excellent work here: Steve On Java
I also found some information from Hinkmond Wong's blog: https://blogs.oracle.com/hinkmond/entry/even_quicker_guide_to_install
I'm pasting a modified version of the conversation and information here for other wandering souls!
METHOD 1 - download & deploy, options for compact profiles
Most Raspberry Pi distributions have been hard float for a while... To check, look for the following file:
/lib/arm-linux-gnueabihf
If this exists, you are running hard float.
Once you have your Pi on a hard float build, grab the latest Java 8 from here:
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
Grab the first one titled "jdk-8-linux-arm-vfp-hflt.tar.gz"
For doing compact profile work to learn how SE Embedded is used (and compact profiles work) go to the downloads on this page: http://www.oracle.com/technetwork/java/embedded/downloads/java-embedded-java-se-download-359230.html
and start with this one: ejdk-8-fcs-b132-linux-arm-vfp-hflt-03_mar_2014.tar.gz (ARMv7 Linux - VFP, HardFP ABI, Little Endian)
then use jrecreate to shrink it.
METHOD 2 - use apt-get on the Raspberry Pi, full "embedded" version of the JDK
From Linux command line >> sudo apt-get update && sudo apt-get install oracle-java8-jdk
Note: see Hinkmond's blog post and an excellent explanation in the comments section on the meaning of SE Embedded
Enjoy!
Brent S

How will the fifth (GND) pin in RS422 be connected in USB 2.0 for making a convertor?

Hi all,
I am looking for a solution to my doubt. The doubt is
What kind of Discrete IO (continuous High or Continuous Low or programmed DIO) may have been used in an equipment which is used just to confirm that the ^Ground Support Equipment (GSE)^ is connected before transferring data on RS422 bus. This DISCRETE is connected with GSE to ensure the data downloading device is connected.

Your image does not make any sense. There are no other lines on usb besides the first four.
How is your question related to NI's digital I/O devices or software?

High Speed RS422

Hi,
I am trying to develop a test program to test an RS422 link recieving a 24 byte message every 2.5ms (on average) and responding to it. I always had concerns about the timing of the messages, and latest testing shows that the software only sees every 11 messages (on average) using a COM CALLBACK to do this. Is this going to be possible in a CVI environment?
Cheers
Stuart

In a recent application we have written we used the following approach:
- create a struct that fits the incoming data package
- use bit fields in the struct (if necessary) to be able to access each component easily
- create a thread-safe variable (or queue) that is able to store package data
- create a thread and loop on the number of bytes in queue
- when available read bytes directly into the struct variable [ComRd (port, &struct_ptr, bytes)], process (header bytes, data id's, checksums) if required, put valuable data into the thread-safe variable (or queue)
- keep the thread running as long as you need it
- test code accesses the thread-safe variable (or queue) when it needs any data from the incoming stream
This has been extremely useful. We completely separated "communication code" from the rest of the "test code" and avoided confusing bit operations within the test related part and used more intuitive struct fields.
The thread became sufficiently fast. We had baud rates of 1,500,000 and packages of different size.
We never missed any data. I know it from the incoming time tags.
Hope this helps,
S. Eren BALCI
www.aselsan.com.tr

What's it like to edit with an RPI of, say, 5?

I've spent quite a bit of time going over the results on the PPBM site. I spent today digging a little more deeply into the RPI figures. Obviously, editing on a machine with an RPI of 1 will give you the best possible experience; the fewest freezes, the least lag, the fastest renders. And an RPI of, say, 20 will be much, much slower. But what if your machine clocks in at, say, 5? You're not at the bottom of the heap, but neither are you close to the top. Does this mean that you're suffering through constant crashes? Do you have to transcode your AVCHD to a different format before editing can even begin? Do you give up entirely on certain effects or limit yourself to just one or two layers? Does scrubbing through the timeline make the baby Jesus cry?
In your personal experience, how slow is too slow? As you slide down the RPI scale from 1 to 5, to 10, etc., at what point does the software become unusable?
Obviously, this is a subjective question, but that's okay, because I'm hoping for some subjective answers.

Clay,
To give you some further insight in how to look at RPI and its merits, or lack thereof, one of the things I'm still struggling with is presenting the test results of the new PPBM6 benchmark in a new format, that makes it easier to interpret where areas of improvement may be with your specific system in comparison to other systems.
Sidebar: This proves to be major hurdle to take, since it requires dynamic SQL queries and calculations of the database and presenting the results in these kind of graphs in a LightBox pop-up window for the selected record.
This may not be the final presentation form, but it will show in an eye-glance what this system does in comparison to other systems.
Short explanation: Each bar shows the rank of this system on a specific test, compared to all other systems expressed as the percentage ranking. So, on Total Time this example ranks at 70%, with 30% scoring higher and 70% scoring lower. On RPI 25% score higher and 75% score lower.
If I look at these results, the overall for Total Time and RPI are quite good for the system in question, but what immediately catches my eye is the excellent Disk I/O results, they are very, very good @ 85%. Additionally, the MPE results are very good @ 81%, but both the MPEG2-DvD and H.264 results are somewhat disappointing with 55% and 64% respectively. So, the overall results are positively influenced by the great Disk I/O performance and to a lesser degree by the good MPE results.
If I were in the dark about this systems configuration, I would guess that this system has a dedicated raid controller with a large array causing this great Disk I/O performance and has a very good video card, but is held back on the other tests by other factors. The fact that H.264 is better than the MPEG2-DVD results shows me that this system is nicely tuned, no superfluous background processes running, is overclocked with a nice amount of memory and is better than a plain quad-core, probably a hexa-core or better, but the MPEG2-DVD results are held back because of the interaction between memory and VRAM, which may indicate an older generation CPU. Also, the degree of overclocking may be limited, increasing the latencies between memory and VRAM.
To go back to my earlier post, if you have to export to multiple formats each day, this is a fabulous result, because of the excellent Disk I/O results, if you have clients looking over your shoulder regularly your video card is great, but if you were to export long timelines from AVCHD to MPEG2-DVD, then you may consider upping memory or overclocking a bit more to make a difference.
Note that this is with the same RPI. Now if you compare different systems, you may find different points of improvement. See for example this presentation form:
Here you see essentially the same info, but presented in a different way.
I prefer this way with the speedometer over the first presentation form, but it is even more difficult to implement, since it entails six separate charts.
Two significant differences in comparison to the earlier chart are the Disk I/O performance, which is lacking in this system in comparison to similar systems and the good MPE performance, which shows a very good video card for this system - but not overall - and which helps the MPEG2-DVD score to achieve nice results. This system is more balanced than the previous example, since the scores match better even when the performance is much lower. Note that the first example showed 55% for the MPEG2-DVD test and this one 51%, but the first one showed a RPI score of 75%, while this system shows 40%. That simply means the first system is pretty weak and this system is very good at exporting to MPEG2-DVD. The second system probably has the better BFTB (Bang-for-the-buck) value of these two systems for exporting to MPEG2-DVD.
Again, I emphasize that RPI is a great way to see overall results compared to similar systems, but you have to delve deeper and investigate individual test results to draw conclusions to help improve your systems performance where it matters most for your workflow.
I hope this helps to explain the value - or lack thereof - of the RPI measurement.
PS. The new PPBM6 results table (you have to be registered and logged in to see these results) shows these kind of rankings in the overview, although not on a scale of 1 - 100%, but as absolute scores ranging from first to last observation.

IMS MDrive 23 with NI RS422 Card (PXI-8431)

Hi,
I am using IMS MDrive 23 Hybrid Motor in our application. I was using IMS supplied RS422 Converter Cable MD-CC4 to commuincate with Motor from LabVIEW. With the MCode programming, I'm able to generate, download, execute and read response from motor using the IMS Converter cable. But to communicate multiple motors, we have procured NI PXI-8431 (8 Port RS422/RS485 card). When I connect the card with motor, using the IMS Terminal (Terminal utility supplied by IMS), I'm getting garbage values like > Ð¤È~ > hRä~? e ÐHè~? Ð¤è~? t ö û Þ Ý í .
I have configured Transmit/Receive Buffer and also the termination to communicate. The end application is based on LabVIEW, IMS terminal is to try viewing. Is there any difference in communicating IMS Motor with IMS RS422 Converter and other Third Party Converter?
Thanks and Regards,
Soundar.
Attachments:
RS422 Data.png ‏20 KB

Hi,
I've had a check to see if we have any known software conflict issues with those cards but it all seems fine, it could be that the Windows Driver layer is causing some issues. If you nip into Device Manager and go to the properties of the 8431 you should be able to change it to 2-wire mode from those settings then re-run the program.
Also does the program throw any errors at all in terms of device resources when trying to move from send to receive mode?
What versions of NI-VISA and NI-Serial do you currently have installed?
Kind Regards,
Applications Engineer

Problem in RS422 data writing in file

I am receving data from data recorder, when we store in file, it stores in character format then for comapring these values, I have to convert it to hex format, as cahracter by character and it takes lot of time.
How we can store it directly in Hex Format, so there may not need to convert it and directly we can extract values from data frame.
Waiting for reply
Regards,
Jitendra

Hi Chris,
Thanks for reply,
I am receving file from RS422 port from Flight Data recorder and it is storing in character format.
In labview how to read and compare directly in hex/decimal. This time What is happening, that this character file I have to convert in HEX character by character file. For 35 KB file, it is taking more then 10 minutes. For 90 minutes recorded data i.e. 40 MB file, It will take time in days.
plz its very urgent, give any solution.
Regards,
Jitendra

Adaptateur usb rs422

Bonjour à tous,
j'ai pour projet de remplacer une partie d'un banc de test tournant sous une autre application par labview.
je travaillerai sous labview 8.2. sur un PC portable équipé d'une interface GPIB, port série RS232, USB.
les 2 systemes de positionnement sont équipés deux moteurs asynchrones raccordés chacun sur un variateur de vitesse le tout raccordé sur un ordi via une carte interface relais (connecteur SUB-37).
deux codeurs absolus permet de retrouner la position du mât et du plateau, chaq codeur est raccordé sur l'ordi via une carte interface par liaison RS422.
Dans un premier temps il me faut gérer un plateau tournant et le déplacement sur un mat d'antenne.
- j'utilise un adaptateur (convertisseur) usb/rs422-2ports pour les deux codeurs: Comment je le configure dans MAX ou Labview pour pouvoir renvoyer les positions dans mon programme labview? ensuite le pourt rs422 fourni l'alim 24Volts à la carte dans le pc. influence pour l'adaptateur usb?
- Peut-on commander les moteurs (en marche avant,arrière et selection de vitesse) via le variateur de vitesse par labview?
Voici rapidement ce qu'il faut pour à mon avis pour gérer le systeme de positionnement des antennes.
Merci de m'aider
cordialement

Bonjour Lamba,
Le driver permettant de lire vos trames RS 422, est le driver NI Serial.
Ensuite pour commander vos moteurs, il vous faut une carte dediée, permettant d'assurer la rotation de votre moteur dans les deux sens....
Une possibilité est d'utiliser l'Offre groupée NI Motion Control.
Si vous souhaitez obtenir plus d'informations concernant les modules nécessaires à votre application, je vous encourage à contacter National Instruments au 01.54.66.24.24.
Je vous souhaite une bonne journée,
Rémi D.
National Instruments France
#adMrkt{text-align: center;font-size:11px; font-weight: bold;} #adMrkt a {text-decoration: none;} #adMrkt a:hover{font-size: 9px;} #adMrkt a span{display: none;} #adMrkt a:hover span{display: block;}
>> Les rencontres techniques de NI - Mesures et acquisition de données : de la théorie à la mise en ...

Quadrature Input and RS422 Signal Levels

I have a quadrature signal coming from a motion control drive that is in RS422 levels. What would the easiest solution be to get those signals into the quadrature encoder module (cFP)?
Thanks,
Michael Wise

http://www.baldor.com/products/motioncontrol/microflex.asp?product.asp?1=1&product=Servo+Controls&fa...
It has a simulated (actual signal to drive is a resolver) quadrature signal coming out. I'm only concerned with A+B since I'm just using it to determine speed. In the spec it says the signal levels of the encoder output conform to RS422 Levels.
I was planning on using the NI cFP-QUAD-510 for reading the encoder A/B signals back into the cFP system.

Scheda pci RS422

salve
stavo cercando delle schede PCI da inserire in un normale PC per leggere i dati provenienti da un'interfaccia seriale RS422.
Mi chiedevo quale scheda posso prendere in modo da gestirla nel modo più semplice possibile tramite LabView

Hi,
the best way to get information on hardware configuration, characteristics and prices is to contact us directly by phone. For RS/422 national instruments hardware look at the web site at the bottom of this page
Regards,
Salve,
il modo migliore per ricevere informazioni di tipo commerciale sui nostri prodotti e' di chiamare il nostro ufficio italiano al numero
02.41.30.91
Per avere una panoramica dei dispositivi RS/422 National Instruments, puo' consultare il seguente sito
NI Serial Interface Hardware
AlessioD
National Instruments

HELP:DAAPI on RPI (Java ME 3.3)

Hello,
I am a beginner when it comes to HW and understanding documentation for that so I'll see if someone on this list can help me. What I am trying to accomplish is to read temperature using a TMP36 sensor (http://www.adafruit.com/products/165). As RPI doesn't have a analog input I am using a MCP3008 ADC (http://www.adafruit.com/products/856) to convert that analog value into a digital value.
The idea is to use the DAAPI SPI APIs to communicate with the MCP3008, and here is where I don't understand how to do this. The MCP3008 doucmentation is here: http://ww1.microchip.com/downloads/en/DeviceDoc/21295d.pdf
The code I am using looks like this (this is not the full source, it is just the part where I am trying to get the temp) and the parts I really would appreciate if someone told me how to is the initialization string (txBuf) and the getTemperature method. As you probably can see I have no clue what I am doing :-)
import com.oracle.deviceaccess.PeripheralManager;
import com.oracle.deviceaccess.PeripheralNotAvailableException;
import com.oracle.deviceaccess.PeripheralNotFoundException;
import com.oracle.deviceaccess.PeripheralTypeNotSupportedException;
import com.oracle.deviceaccess.spibus.SPIDevice;
import java.io.IOException;
* @author atael
public class TMP36 {
    private static SPIDevice mcp3008 = null;
    private static final String SPIDEVICE_NAME = "SPI_Slave";
    public static boolean connect() {
        boolean isConnected = false;
        try {
            mcp3008 = (SPIDevice) PeripheralManager.open(SPIDEVICE_NAME,SPIDevice.class, null);
            // Configuration - from the docs reading CH0 (TMP 36 connected there)
            // .... ...S S210 xxxx xxxx xxxx
            // 0000 0001 1000 0000 0000 0000
            byte[] txBuf = { (byte)0x01, (byte)0x40, (byte)0x00 };
            mcp3008.begin();
            mcp3008.write(txBuf, 0, txBuf.length);
            mcp3008.end();
            isConnected = true;
        } catch (PeripheralNotAvailableException ex) {
            ex.printStackTrace();
        } catch (PeripheralNotFoundException ex) {
            ex.printStackTrace();
        } catch (PeripheralTypeNotSupportedException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        return isConnected;
    public static void disconnect () {
        if (mcp3008 != null) {
            try {
                mcp3008.close();
            } catch (IOException ex) {
                ex.printStackTrace();
    public static int getTemperature () {
        try {
            mcp3008.begin();
            mcp3008.write(0x00);
            int value = mcp3008.read();
            mcp3008.end();
            return value;
        } catch (PeripheralNotAvailableException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        return 0;
}Edited by: A Tael on Mar 28, 2013 12:16 PM
Edited by: A Tael on Mar 28, 2013 12:21 PM
Edited by: A Tael on Mar 28, 2013 12:22 PM

Hello Sergey,
you are probably correct, so I changed the code to look like this:
package tmp36rpi;
import com.oracle.deviceaccess.PeripheralManager;
import com.oracle.deviceaccess.PeripheralNotAvailableException;
import com.oracle.deviceaccess.PeripheralNotFoundException;
import com.oracle.deviceaccess.PeripheralTypeNotSupportedException;
import com.oracle.deviceaccess.spibus.SPIDevice;
import java.io.IOException;
* @author atael
public class TMP36 {
    private static SPIDevice mcp3008 = null;
    private static final String SPIDEVICE_NAME = "SPI_Slave";
    public static boolean connect() {
        boolean isConnected = false;
        try {
            mcp3008 = (SPIDevice) PeripheralManager.open(SPIDEVICE_NAME,SPIDevice.class, null);
            byte[] rxBuf = new byte[3];
            byte[] txBuf = new byte[3];
            txBuf[0] = (byte) 1;
            txBuf[1] = (byte) ((8 + 0) << 4);
            txBuf[2] = (byte) 0;
            mcp3008.begin();
            mcp3008.writeAndRead(txBuf, 0, txBuf.length, rxBuf, 0, rxBuf.length);
            mcp3008.end();
            isConnected = true;
        } catch (PeripheralNotAvailableException ex) {
            ex.printStackTrace();
        } catch (PeripheralNotFoundException ex) {
            ex.printStackTrace();
        } catch (PeripheralTypeNotSupportedException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        return isConnected;
    public static void disconnect () {
        if (mcp3008 != null) {
            try {
                mcp3008.close();
            } catch (IOException ex) {
                ex.printStackTrace();
    public static int getTemperature () {
        try {
            byte[] rxBuf = new byte[3];
            byte[] txBuf = new byte[3];
            txBuf[0] = (byte) 1;
            txBuf[1] = (byte) ((8 + 0) << 4);
            txBuf[2] = (byte) 0;
            mcp3008.begin();
            mcp3008.writeAndRead(txBuf, 0, txBuf.length, rxBuf, 0, rxBuf.length);
            mcp3008.end();
            System.out.println("0: " + (int)rxBuf[0]);
            System.out.println("1: " + (int)rxBuf[1]);
            System.out.println("2: " + (int)rxBuf[2]);
            return ((rxBuf[1] & 3) << 8) + rxBuf[2];
        } catch (PeripheralNotAvailableException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        return 0;
}And when I run my IMLet I get the following in the console:
* MCP3008/TMP36 Thermometer Sample    *
Trying...
0: 1
1: 1
2: 1
MCP3008Checker start is OK.
0: -1
1: -1
2: -1
Temp: 767
[AMS-TRACE] MIDlet:TMP36rpi status=2
[AMS-TRACE] MIDlet:TMP36rpi status=1
0: 1
1: 1
2: 1
Temp: 0
0: 1
1: 1
2: 1
Temp: 0
0: 1
1: 1
2: 1
Temp: 0
0: 1
1: 1
2: 1
Temp: 0
0: 1
1: 1
2: 1
Temp: 0
[AMS-TRACE] MIDlet:TMP36rpi status=3
[AMS-INFO] MIDlet:TMP36rpi terminatedNot sure what I am doing wrong here at all. I have added the rest of the code below:
package tmp36rpi;
import java.util.Timer;
import java.util.TimerTask;
* @author atael
public class MCP3008Checker extends TimerTask {
    private Timer timer;
    private static int INTERVAL_MS = 5000;
    private int temperature;
    private String name;
    MCP3008Checker( String name){
        this.name = name;
    public boolean start () {
        boolean isStarted = false;
        System.out.println ("Trying...");
        if (TMP36.connect()) {
            timer = new Timer();
            timer.schedule(this, 0, INTERVAL_MS);
            temperature = TMP36.getTemperature();
            isStarted = true;
        return isStarted;
    public void run() {
        int newTemperature = TMP36.getTemperature();
        if (newTemperature != temperature) {
            temperature = newTemperature;
        System.out.println("Temp: " + temperature );
    public void stop () {
        if (timer != null) {
            timer.cancel ();
        TMP36.disconnect();
}and
package tmp36rpi;
import javax.microedition.midlet.*;
* @author atael
public class IMlet extends MIDlet {
    private MCP3008Checker mcp3008Checker;
    private static final String name = "MCP3008";
    public void startApp() {
        System.out.println("***************************************");
        System.out.println("* MCP3008/TMP36 Thermometer Sample    *");
        System.out.println("***************************************");
        mcp3008Checker = new MCP3008Checker(name);
        if (mcp3008Checker.start() ) {
            System.out.println("MCP3008Checker start is OK.");
        } else {
            System.out.println("MCP3008Checker start has failed.");
    public void pauseApp() {
    public void destroyApp(boolean unconditional) {
        if (mcp3008Checker != null) {
            mcp3008Checker.stop();
}--Andy
Edited by: A Tael on Apr 2, 2013 1:12 PM

Keyspan USA 28XG RS422 Adapter Not Communicating?

I'm trying to install a Keyspan USA 28XG USB-to-RS422 adapter on a G5 Quad FCP 6.0.4 system, and cannot get it to communicate with a PVW-2800, DSR-1600, or DSR-45. I have followed all installation instructions, used newest v2.5 driver, confirmed ports in the Keyspan Serial Assistant application, and spent 40 minutes on the phone with Keyspan tech support personnel who had never heard of Final Cut Pro (I had to spell it). Their bottom line was basically "it's not us, it's them", suggesting I contact the software manufacturer for support, "if they are still in business." I've searched these boards, and haven't found anything specific enough to help. Anyone using one of these? Brian Conner? Zeb?
Thanks guys,
tim

Hung Ton Quoc wrote:
Sure it's working fine for me (10.5.5)
- Connect the keyspan to a USB Port and connect your serial cable to Keyspan port 1.
- install the driver (that's it : don't open Keyspan serial assistant.
I followed the instructions which said to install the driver first, then connect the adapter. I have now uninstalled the driver, rebooted, and followed your steps, but I still have no communication. I'm about ready to throw it away!
Keyspan Driver v2.5
In the preset, I have:
*Protocol: Sony RS-422*
*Audio Mapping: 2-Channels*
*Time Source: LTC*
*Port: KeySerial1*
*Frame Rate: 29.97*
*Default Timecode: Drop-Frame*
I've also tried *Use Deck Search Mechanism* checked and unchecked.
Thanks for your help. I don't know what else there is to do other than what you said. I'm going to verify the pin-out on the 8-pin to 9-pin cable, but it is a brand new Pipeline Digital CM9 cable which is supposed to work. I wish I had a way to verify communication on the Keyspan ports, other than FCP.
tim

Connecting RS422 Quad Encoder to NI 6602

I have 4 Quadrature Encoder that output RS422 signals that I would like to connect to the NI-6602 board. Will the differential signal levels of the RS422 match with NI-6602 counter timers inputs? Does any one have an example of the pin numbers to connect the A,!A,B,!B,Z and !Z signals to for the NI-6602 card.
Here is the PDF to the NI-6602 Counter Timer board:
http://www.ni.com/pdf/products/us/4daqsc386-393_386-387.pdf
Thanks for your help.

Hello,
If your "RS 422 signal" is a pulse going from 0V to 5V, then they should match with the inputs with your NI-6602. Chapter 4 of the manual found here describes how to make the necessary I/O connections for your board.
Hope this helps,
LA

Can i implement RS422 protocol using 7831 RIO card

please tell if i can implement RS422 protocol using NI FPGA card. Also please help me on how to do the same...

You can definitely implement the RS-422 protocol on the FPGA card. Check out the RS-232 on FPGA example on DevZone. RS-422 may be a bit different than RS-232, but not very much. The main thing you will have to deal with are the voltage levels of the signal. The FPGA DIO are single-ended 3.3V TTL, while RS-422 is a differential voltage signal. So to have a true RS-422 interface you will need to add a signal translator between the FPGA card and your RS-422 device(s).
Christian L
Christian Loew, CLA
Principal Systems Engineer, National Instruments
Please tip your answer providers with kudos.
Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system,
or for use in hazardous environments. You assume all risks for use of the Code and use of the Code is subject
to the Sample Code License Terms which can be found at: http://ni.com/samplecodelicense

Javacomm20_win32 works for RS422?

Hello to all.
I am using the javax.comm api for the RS 232 communication and it works fine. I tried also to communicate with a RS422 by using a serial cable and and a converter from RS232 to RS422 but it dint't work. Does anyone know if the api supports also communication between serial ports RS422?
Does anybody know how to read and send data from the RS 422 interface using the Java language with a Windows OS ?
Thanks in advance
Mandy

If everything is ok without the 422 converter then it may be that some
handshaking signals (RTS/CTS etc) are not wired correctly at the 422
converter [ ... ]IIRC RS422 just uses two wires (for their differential line drivers), IOW
there are no RTS/CTS lines at all.
or between the 232 port and the converter. Check the spec for the
converter and make sure it is wired properly, also check that TX+/-
and RX+/- are wired the right way round.Same here; I run stuff using very long RS485 lines (and a converter box)
which is almost identical to an RS422 configuration except for one thing,
those RS422 drivers are always enabled while the RS485 drivers can
have a third 'tri-state' (both lines at 2.5V IIRC again).
I suspect that the OP should have a look at that converter box.
@OP: did you ever manage to communicate anything between your
device and your PC using e.g. telnet?
kind regards,
Jos

RS422 on RPI

Similar Messages

Maybe you are looking for