chrome.usb.findDevices not working shows error message Failed to open device: Entity not found in chrome://device-log/

[Santinath Mishra]

Hi Folks,

I am developing a chrome app to communicate to HID device using chrome.usb APIs. I am using below chrome APIs

1. chrome.usb.findDevices

2. chrome.usb.controlTransfer

So far I am not able to make it work. chrome://device-log/ shows below error message. 

USBEvent[13:54:01] Failed to open device: Entity not found

I am using right VendorId and ProductId in decimal format, Which I have extracted from device manager info.

Does anyone know about this issue? Any kind of help will be highly appreciated.

Below is the code snippet I am using.

    chrome.usb.findDevices(DEVICE_INFO, function (devices) {

        if (!devices || !devices.length) {

            console.log('device not found');

        }

        console.log("Devices: " + devices);

        console.log(devices[0]);

 var TransferData = {

    "requestType": "class",

    "recipient": "interface",

    "direction": "out",

    "request": 0xx9,

    "value": 0xxx0,

    "index": 0,

   "data": new Uint8Array([00,05, 47, 76, 66, 48, 47,00]).buffer

  };

        setTimeout(function () {

            chrome.usb.controlTransfer(devices[0], TransferData, function (config) {

                if (chrome.runtime.lastError) {

                    console.log(chrome.runtime.lastError);

                } else {

                    console.log('Data Transfer completed');

                }

            });

        }, 3000);

    });

[Reilly Grant]

Questions like this are better answered on Stack Overflow. Please include extra details such as:

1. What console log messages are printed by your code.

2. The value of chrome.runtime.lastError if it is set.

3. A larger snippet of chrome://device-log.

4. Why your are using the chrome.usb API instead of the chrome.hid API. If the device is recognized by the system as HID then it will not be available via chrome.usb.findDevices.

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[Alex Vallee]

Answered here: http://stackoverflow.com/q/36187835/5387

[Santinath Mishra]

Thanks Reilly for your reply.

Here is my log message

Script.js:42 App was granted the "usbDevices" permission.

Script.js:50 Devices: [object Object]

Script.js:51 Object {handle: 2, productId: 34, vendorId: 4323}

Script.js:57  Data Transfer completed

chrome.runtime.lastError is set to undefined

I have also tried using chrome.hid API, here are the code snippet and error message

Error message

Device Length: 1

mychromeapp.js:109 Found device: 9

mychromeapp.js:112 ProductId: 34

mychromeapp.js:113 VendorId: 4323

mychromeapp.js:118 Connected to the HID device!

mychromeapp.js:119 ObjectconnectionId: 6__proto__: Object

mychromeapp.js:150 Info received by device

extensions::lastError:133 Unchecked runtime.lastError while running hid.send: Transfer failed.

    at Object.callback (chrome-extension://nnchpnlblaiehgoljobkmbfhenneaejp/mychromeapp.js:149:20)reportIfUnchecked @ extensions::lastError:133

Sample code using chrome.hid

 

var  VENDOR_ID = 4323;  

var  PRODUCT_ID = 34;  

var DEVICE_INFO = { "vendorId": VENDOR_ID, "productId": PRODUCT_ID };

 

 

chrome.hid.getDevices(DEVICE_INFO, function(devices) {

console.log('Device Length: '+devices.length);

if (!devices || !devices.length) {

 console.log('device not found');

 return;

}

console.log('Found device: ' + devices[0].deviceId);

myHidDevice = devices[0].deviceId;

       

console.log('ProductId: '+devices[0].productId.toString(16));

console.log('VendorId: '+devices[0].vendorId.toString(16));

 

  chrome.hid.connect(myHidDevice, function(connection) {

console.log('Connected to the HID device!');

console.log(connection);

connectionId = connection.connectionId;

var arrayLength = 24;

var message = new Uint8Array(arrayLength);

message[0] = 0x05; 

message[1] = 0x2F; 

message[2] = 0x43; 

message[3] = 0x4C; 

message[4] = 0x3C; 

message[5] = 0x2F; 

for (var i = 6; i < arrayLength; i++) {

message[i] = 0x00;

}

var TransferData = {

"requestType": "class",

"recipient": "interface",

"direction": "out",

"request": 0x09,

"value": 0x0300,

"index": 0,

"data": message.buffer

};

        chrome.hid.send(connectionId,0, message.buffer, function() {

console.log("Info received by device");

}); 

  });

});

[Reilly Grant]

In the first example you have there the transfer is completing successfully. The error you see in chrome://device-log is likely not related. There are often failures that show up there during device enumeration and unfortunately it doesn't tell you which device the error was related to.