I need to Read data from USB scale, DYMO s100 scale. which Java package is going to work the best?

Question

I have tried using LibUsb to connect I just really need to be able to parse the data from this scale, in the end it is going to be going into Filemaker pro. the issue I have with this current code:

package Model;

import javax.management.Descriptor;
import javax.usb.UsbDevice;
import javax.usb.UsbDeviceDescriptor;
import javax.usb.UsbHub;

import org.usb4java.*;

import java.nio.ByteBuffer;
import java.util.List;

public class main {

    //Vendor ID = 0x0922
    //Product ID = 0x8009
    private static short Vendor_ID = 0x0922;
    private static short Product_ID = (short) 0x8009;

    public static void main(String[] args) {

        Device Dymo_Scale = listDevices(Vendor_ID, Product_ID);

        DeviceHandle handle = new DeviceHandle();
        int result = LibUsb.open(Dymo_Scale, handle);
        if (result != LibUsb.SUCCESS) throw new LibUsbException("Unable to open USB device", result);
        try
        {
            result = LibUsb.setConfiguration(handle, 0);
            if (result != LibUsb.SUCCESS) throw new LibUsbException("Unable to set Configuration", result);
            // Use device handle here
            result = LibUsb.claimInterface(handle, 0);
            if (result != LibUsb.SUCCESS) throw new LibUsbException("Unable to claim interface", result);
            try
            {
                ByteBuffer buffer = ByteBuffer.allocateDirect(8);
                buffer.put(new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 });
                int transfered = LibUsb.controlTransfer(handle,
                        (byte) (LibUsb.REQUEST_TYPE_CLASS | LibUsb.RECIPIENT_INTERFACE),
                        (byte) 0, (short) 0, (short) 0, buffer, 5);
                if (transfered < 0) throw new LibUsbException("Control transfer failed", transfered);
                System.out.println(transfered + " bytes sent");
            }
            finally
            {
                result = LibUsb.releaseInterface(handle, 0);
                if (result != LibUsb.SUCCESS) throw new LibUsbException("Unable to release interface", result);
            }
        }
        finally
        {
            LibUsb.close(handle);
        }


    }





    private static Device listDevices(short vendorId, short productId) {
        // Create the libusb context
        Context context = new Context();

        // Initialize the libusb context
        int result = LibUsb.init(context);
        if (result < 0)
        {
            throw new LibUsbException("Unable to initialize libusb", result);
        }

        // Read the USB device list
        DeviceList list = new DeviceList();
        result = LibUsb.getDeviceList(context, list);
        if (result < 0)
        {
            throw new LibUsbException("Unable to get device list", result);
        }

        try
        {
            // Iterate over all devices and list them
            for (Device device: list)
            {
                int address = LibUsb.getDeviceAddress(device);
                int busNumber = LibUsb.getBusNumber(device);
                DeviceDescriptor descriptor = new DeviceDescriptor();
                result = LibUsb.getDeviceDescriptor(device, descriptor);
                if (result < 0)
                {
                    throw new LibUsbException(
                            "Unable to read device descriptor", result);
                }
                if (descriptor.idVendor() == vendorId && descriptor.idProduct() == productId) return device;

            }
        }
        finally
        {
            // Ensure the allocated device list is freed
            LibUsb.freeDeviceList(list, true);
        }

        // Deinitialize the libusb context
        LibUsb.exit(context);
        return null;
    }

}

is I get a USB error:

Exception in thread "main" org.usb4java.LibUsbException: USB error 9: Control transfer failed: Pipe error
    at Model.main.main(main.java:41)

Process finished with exit code 1

I have quite a bit of experience with java itself in networking and other areas. I think my issue might be somewhere in the ByteBuffer area... I am not exactly sure about endpoints or buffers I am also trying to access the device through interface 0 which it seems to make the connection and claim the Interface just fine but I need now to get a reading back from the scale...

Is there a better Package out there that can do what I am looking for? or is there just something I am not doing properly in the Synchronous data transfer. Currently am writing this on a Mac if that makes any bit of difference.

As always, appreciate the help if any can provide.

• Side note. This is a decently old package and has not been updated in years. Wonder if there is an updated more recent option.

Answer 1

Figured out the issue. I was sending 8 bytes.. scale looks for 6, although dymo does not say this anywhere. their manual is a joke... and they have no documentation. Main.java:

package Model;

import javax.management.Descriptor;
import javax.usb.*;
import javax.usb.event.UsbPipeListener;

import org.usb4java.*;

import java.nio.ByteBuffer;
import java.util.List;

public class main{

    //Vendor ID = 0x0922
    //Product ID = 0x8009
    private static short Vendor_ID = 0x0922;
    private static short Product_ID = (short) 0x8009;

    public static void main(String[] args) throws UsbException {
        UsbScaleInterface scale = UsbScaleInterface.findScale();
        scale.open();
        try {
            for (int i = 0; i < 60; i++) {
                scale.syncSubmit();
            }
        } finally {
            scale.close();
        }
    }

}

UsbScaleInterface.java:

package Model;

import javax.usb.*;
import javax.usb.event.UsbPipeDataEvent;
import javax.usb.event.UsbPipeErrorEvent;
import javax.usb.event.UsbPipeListener;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

public class UsbScaleInterface  implements UsbPipeListener {

    private final UsbDevice device;
    private UsbInterface iface;
    private UsbPipe pipe;
    private byte[] data = new byte[6];

    private UsbScaleInterface(UsbDevice device) {
        this.device = device;
    }


    public static UsbScaleInterface findScale() throws UsbException {
        UsbServices services = UsbHostManager.getUsbServices();
        UsbHub rootHub = services.getRootUsbHub();
        // Dymo M10 Scale:
        UsbDevice device = findDevice(rootHub, (short) 0x0922, (short) 0x8003);
        // Dymo M25 Scale:
        if (device == null) {
            device = findDevice(rootHub, (short) 0x0922, (short) 0x8004);
        }
        // Dymo S100 Scale:
        if (device == null) {
            device = findDevice(rootHub, (short) 0x0922, (short) 0x8009);
        }
        if (device == null) {
            return null;
        }
        return new UsbScaleInterface(device);
    }

    private static UsbDevice findDevice(UsbHub hub, short vendorId, short productId) {
        for (UsbDevice device : (List<UsbDevice>) hub.getAttachedUsbDevices()) {
            UsbDeviceDescriptor desc = device.getUsbDeviceDescriptor();
            if (desc.idVendor() == vendorId && desc.idProduct() == productId) {
                return device;
            }
            if (device.isUsbHub()) {
                device = findDevice((UsbHub) device, vendorId, productId);
                if (device != null) {
                    return device;
                }
            }
        }
        return null;
    }

    public void open() throws UsbException {
        UsbConfiguration configuration = device.getActiveUsbConfiguration();
        iface = configuration.getUsbInterface((byte) 0);
        // this allows us to steal the lock from the kernel
        iface.claim(usbInterface -> true);
        final List<UsbEndpoint> endpoints = iface.getUsbEndpoints();
        pipe = endpoints.get(0).getUsbPipe(); // there is only 1 endpoint
        pipe.addUsbPipeListener(this);
        pipe.open();
    }

    public void syncSubmit() throws UsbException {
        pipe.syncSubmit(data);
    }


    public void close() throws UsbException {
        pipe.close();
        iface.release();
    }

    @Override
    public void dataEventOccurred(UsbPipeDataEvent upde) {
        boolean empty = data[1] == 2;
        boolean overweight = data[1] == 6;
        boolean negative = data[1] == 5;
        boolean grams = data[2] == 2;
        int scalingFactor = data[3];
        int weight = (data[4] & 0xFF) + (data[5] << 8);
        if (empty) {
            System.out.println("EMPTY");
        } else if (overweight) {
            System.out.println("OVERWEIGHT");
        } else if (negative) {
            System.out.println("NEGATIVE");
        } else { // Use String.format since printf causes problems on remote exec
            System.out.println(String.format("Weight = %,.1f%s",
                    scaleWeight(weight, scalingFactor),
                    grams ? "g" : "oz"));
        }
    }

    private double scaleWeight(int weight, int scalingFactor) {
        return weight * Math.pow(10, scalingFactor);
    }


    @Override
    public void errorEventOccurred(UsbPipeErrorEvent usbPipeErrorEvent) {
        Logger.getLogger(UsbScaleInterface.class.getName()).log(Level.SEVERE, "Scale Error", usbPipeErrorEvent);
    }
}

Just need to figure out how the tare function might work now and possible way to turn the scale on from the computer. however I don't think this will be an easy task as it would be pretty brute force... Mind you both of these classes are in the same package.