diff --git a/scratch_extensions/scratch_deviceManager.js b/scratch_extensions/scratch_deviceManager.js
index a50a7e2..18fe165 100644
--- a/scratch_extensions/scratch_deviceManager.js
+++ b/scratch_extensions/scratch_deviceManager.js
@@ -1,91 +1,99 @@
 // Communicate with the Scratch Device Manager through Socket.IO
 window.ScratchDeviceManager = new (function () {
-    var self = this;
+    var instance = this;
+    var sockets = [];
+
+    // Assume it's OK until we find out otherwise
+    var isConnected = true;
 
     // device-manager.scratch.mit.edu = 127.0.0.1
-    self.deviceManagerHost = 'https://device-manager.scratch.mit.edu:3030';
+    instance.deviceManagerHost = 'https://device-manager.scratch.mit.edu:3030';
 
     // work around https://github.com/socketio/socket.io-client/issues/812
     function connectNamespace(namespace) {
-        return io(self.deviceManagerHost + namespace, {forceNew: true});
+        return io(instance.deviceManagerHost + namespace, {forceNew: true});
+    }
+
+    function onClose(){
+        for(var i=0; i<sockets.length; i++){
+            sockets[i].disconnect();
+        } 
     }
 
-    self.wedo2_list = function (callback) {
-        $.ajax(self.deviceManagerHost + '/wedo2/list', {
-            dataType: 'text',
+    window.onbeforeunload = onClose;
+
+    instance.device_list = function (ext_type, ext_name, device_spec, callback) {
+        var url = instance.deviceManagerHost + '/' + ext_type + '/list';
+        var data = {
+            name: ext_name,
+            spec: device_spec
+        };
+        $.ajax(url, {
+            data: {data: JSON.stringify(data)},
+            dataType: 'json',
             success: function (data, textStatus, jqXHR) {
-                var deviceList = JSON.parse(data);
-                if (deviceList.constructor == Array) {
-                    callback(deviceList);
+                isConnected = true;
+                if (data.constructor == Array) {
+                    callback(data, ext_type, ext_name);
                 }
+            },
+            error: function (jqXHR, textStatus, errorThrown) {
+                isConnected = false;
             }
         });
     };
 
-    // TODO: handle multiple devices
-    self.wedo2_open = function (deviceId, callback) {
-        var socket = connectNamespace('/wedo2');
-        var pluginDevice = new RawWeDo2(deviceId, socket);
-        socket.on('deviceWasOpened', function (event) {
-            callback(pluginDevice);
-        });
-        socket.emit('open', {deviceId: deviceId});
-    };
-
-    function RawWeDo2(deviceId, socket) {
-        var WeDo = this;
-        var eventHandlers = {};
-
-        WeDo.close = function() {
-            socket.close();
-        };
-
-        WeDo.setMotorOn = function(motorIndex, power) {
-            socket.emit('motorOn', {motorIndex:motorIndex, power:power});
-        };
-
-        WeDo.setMotorOff = function(motorIndex) {
-            socket.emit('motorOff', {motorIndex:motorIndex});
-        };
-
-        WeDo.setMotorBrake = function(motorIndex) {
-            socket.emit('motorBrake', {motorIndex:motorIndex});
-        };
-
-        WeDo.setLED = function(rgb) {
-            socket.emit('setLED', {rgb:rgb});
-        };
+    // Attempt to open a device-specific socket connection to the Device Manager.
+    // This must call `callback` exactly once no matter what.
+    // The callback will receive a connected socket on success or `null` on failure.
+    instance.socket_open = function (ext_name, deviceType, deviceId, callback) {
+        function onDeviceWasOpened () {
+            // If this is the first event on this socket then respond with success.
+            if (clearOpenTimeout()) {
+                callback(socket);
+            }
+        }
 
-        WeDo.playTone = function(tone, durationMs) {
-            socket.emit('playTone', {tone:tone, ms:durationMs});
-        };
+        function onDisconnect () {
+            var socketIndex = sockets.indexOf(socket);
+            if (socketIndex >= 0) {
+                sockets.splice(socketIndex, 1);
+            }
+            // If this is the first event on this socket then respond with failure.
+            if (clearOpenTimeout()) {
+                callback(null);
+            }
+        }
 
-        WeDo.stopTone = function() {
-            socket.emit('stopTone');
-        };
+        function onTimeout () {
+            // This will trigger `onDisconnect()`
+            socket.disconnect();
+        }
 
-        function setHandler(eventName, handler) {
-            if (eventHandlers.hasOwnProperty(eventName)) {
-                var oldHandler = eventHandlers[eventName];
-                if (oldHandler) {
-                    socket.removeListener(eventName, oldHandler);
-                }
+        // If the timeout is still pending, clear it and return true. Otherwise, return false.
+        // Callers can use the return value to determine whether they are the first to respond on this socket.
+        function clearOpenTimeout () {
+            if (openTimeout !== null) {
+                clearTimeout(openTimeout);
+                openTimeout = null;
+                return true;
             }
-            if (handler) {
-                socket.on(eventName, handler);
+            else {
+                return false;
             }
-            eventHandlers[eventName] = handler;
         }
 
-        // function handler(event) { access event.sensorName and event.sensorValue }
-        WeDo.setSensorHandler = function (handler) {
-            setHandler('sensorChanged', handler);
-        };
+        var socket = connectNamespace('/' + deviceType);
+        sockets.push(socket);
 
-        WeDo.setDeviceWasClosedHandler = function (handler) {
-            // TODO: resolve this ambiguity
-            setHandler('disconnect', handler);
-            setHandler('deviceWasClosed', handler);
-        };
-    }
+        socket.on('deviceWasOpened', onDeviceWasOpened);
+        socket.on('disconnect', onDisconnect);
+        var openTimeout = setTimeout(onTimeout, 10 * 1000);
+
+        socket.emit('open', {deviceId: deviceId, name: ext_name});
+    };
+
+    instance.isConnected = function () {
+        return isConnected;
+    };
 })();
diff --git a/scratch_extensions/scratch_ext.js b/scratch_extensions/scratch_ext.js
index 75d0fd9..c9cc950 100644
--- a/scratch_extensions/scratch_ext.js
+++ b/scratch_extensions/scratch_ext.js
@@ -106,8 +106,13 @@ window.ScratchExtensions = new (function () {
         var callback = function (retval) {
             Scratch.FlashApp.ASobj.ASextensionReporterDone(ext_name, job_id, retval);
         };
-        args.push(callback);
-        handlers[ext_name][reporter].apply(handlers[ext_name], args);
+        if(handlers[ext_name]._getStatus().status != 2){
+            callback(false); 
+        }
+        else{
+            args.push(callback);
+            handlers[ext_name][reporter].apply(handlers[ext_name], args);
+        }
     };
 
     lib.getReporterForceAsync = function (ext_name, reporter, args, job_id) {
@@ -134,8 +139,9 @@ window.ScratchExtensions = new (function () {
 
         if (ext_name in deviceSpecs) {
             switch (deviceSpecs[ext_name].type) {
+                case 'ble':
                 case 'wedo2':
-                    if (!ScratchDeviceManager) {
+                    if (!(ScratchDeviceManager && ScratchDeviceManager.isConnected())) {
                         return {status: 0, msg: 'Missing Scratch Device Manager'};
                     }
                     break;
@@ -195,29 +201,28 @@ window.ScratchExtensions = new (function () {
                     if (!awaitingSpecs['hid']) awaitingSpecs['hid'] = {};
                     awaitingSpecs['hid'][spec.vendor + '_' + spec.product] = ext_name;
                 }
-                else if (spec.type == 'serial') {
-                    awaitingSpecs['serial'] = ext_name;
-                }
-                else if (spec.type == 'wedo2') {
-                    awaitingSpecs['wedo2'] = ext_name;
+                else {
+                    awaitingSpecs[spec.type] = ext_name;
                 }
             }
         }
 
-        if (plugin) {
-            if (awaitingSpecs['hid']) {
+        for (var specType in awaitingSpecs) {
+            if (!awaitingSpecs.hasOwnProperty(specType)) continue;
+
+            if (plugin && specType == 'hid') {
+                var awaitingHid = awaitingSpecs['hid'];
                 plugin.hid_list(function (deviceList) {
-                    var hidList = awaitingSpecs['hid'];
                     for (var i = 0; i < deviceList.length; i++) {
-                        var ext_name = hidList[deviceList[i]["vendor_id"] + '_' + deviceList[i]["product_id"]];
-                        if (ext_name) {
-                            handlers[ext_name]._deviceConnected(new HidDevice(deviceList[i], ext_name));
+                        var deviceID = deviceList[i]["vendor_id"] + '_' + deviceList[i]["product_id"];
+                        var hid_ext_name = awaitingHid[deviceID];
+                        if (hid_ext_name) {
+                            handlers[hid_ext_name]._deviceConnected(new HidDevice(deviceList[i], hid_ext_name));
                         }
                     }
                 });
             }
-
-            if (awaitingSpecs['serial']) {
+            else if (plugin && specType == 'serial') {
                 ext_name = awaitingSpecs['serial'];
                 plugin.serial_list(function (deviceList) {
                     for (var i = 0; i < deviceList.length; i++) {
@@ -225,15 +230,10 @@ window.ScratchExtensions = new (function () {
                     }
                 });
             }
-        }
-
-        if (ScratchDeviceManager && awaitingSpecs['wedo2']) {
-            ext_name = awaitingSpecs['wedo2'];
-            ScratchDeviceManager.wedo2_list(function(deviceList) {
-                for (var i = 0; i < deviceList.length; ++i) {
-                    handlers[ext_name]._deviceConnected(new WeDo2Device(deviceList[i].id || deviceList[i], ext_name));
-                }
-            });
+            else if (ScratchDeviceManager) {
+                ext_name = awaitingSpecs[specType];
+                ScratchDeviceManager.device_list(specType, ext_name, deviceSpecs[ext_name], deviceListCallback);
+            }
         }
 
         if (!shouldLookForDevices()) {
@@ -241,6 +241,15 @@ window.ScratchExtensions = new (function () {
         }
     }
 
+    function deviceListCallback(deviceList, ext_type, ext_name) {
+        for (var i = 0; i < deviceList.length; ++i) {
+            var deviceConstructor = Devices[ext_type];
+            var deviceId = deviceList[i].id || deviceList[i];
+            var device = new deviceConstructor(deviceId, ext_type, ext_name);
+            handlers[ext_name]._deviceConnected(device);
+        }
+    }
+
     function checkPolling() {
         if (poller || !shouldLookForDevices()) return;
 
@@ -265,27 +274,33 @@ window.ScratchExtensions = new (function () {
     function createDevicePlugin() {
         if (plugin) return;
 
-        // TODO: delegate more of this to the other files
-        if (isOffline) {
-            // Talk to the AIR Native Extension through the offline editor's plugin emulation.
-            plugin = Scratch.FlashApp.ASobj.getPlugin();
-        } else if (window.ScratchDeviceHost && window.ScratchDeviceHost.isAvailable()) {
-            // Talk to the Native Messaging Host through a Chrome extension.
-            plugin = window.ScratchDeviceHost;
-        } else {
-            if (window.ScratchPlugin.useActiveX) {
-                // we must be on IE or similar
-                plugin = new ActiveXObject(window.ScratchPlugin.axObjectName);
+        try {
+            // TODO: delegate more of this to the other files
+            if (isOffline) {
+                // Talk to the AIR Native Extension through the offline editor's plugin emulation.
+                plugin = Scratch.FlashApp.ASobj.getPlugin();
+            } else if (window.ScratchDeviceHost && window.ScratchDeviceHost.isAvailable()) {
+                // Talk to the Native Messaging Host through a Chrome extension.
+                plugin = window.ScratchDeviceHost;
             } else {
-                // Not IE: try NPAPI
-                var pluginContainer = document.createElement('div');
-                document.getElementById('scratch').parentNode.appendChild(pluginContainer);
-                pluginContainer.innerHTML =
-                    '<object type="application/x-scratchdeviceplugin" width="1" height="1"> </object>';
-                plugin = pluginContainer.firstChild;
+                if (window.ScratchPlugin.useActiveX) {
+                    // we must be on IE or similar
+                    plugin = new ActiveXObject(window.ScratchPlugin.axObjectName);
+                } else {
+                    // Not IE: try NPAPI
+                    var pluginContainer = document.createElement('div');
+                    document.getElementById('scratch').parentNode.appendChild(pluginContainer);
+                    pluginContainer.innerHTML =
+                        '<object type="application/x-scratchdeviceplugin" width="1" height="1"> </object>';
+                    plugin = pluginContainer.firstChild;
+                }
+                // Talk to the actual plugin, but make it pretend to be asynchronous.
+                plugin = new window.ScratchPlugin.PluginWrapper(plugin);
             }
-            // Talk to the actual plugin, but make it pretend to be asynchronous.
-            plugin = new window.ScratchPlugin.PluginWrapper(plugin);
+        }
+        catch (e) {
+            console.error('Error creating plugin or wrapper:', e);
+            plugin = null;
         }
 
         // Wait a moment to access the plugin and claim any devices that plugins are
@@ -383,13 +398,70 @@ window.ScratchExtensions = new (function () {
         };
     }
 
-    // TODO: create a base class for these device classes so that we can share common code
-    function WeDo2Device(id, ext_name) {
+    function WeDo2Device(id, ext_type, ext_name) {
         var dev = null;
+        this.ext_type = ext_type;
+        this.ext_name = ext_name;
         var self = this;
-
         this.id = id;
 
+        function RawWeDo2(deviceId, socket) {
+            var WeDo = this;
+            var eventHandlers = {};
+    
+            WeDo.close = function() {
+                socket.close();
+            };
+    
+            WeDo.setMotorOn = function(motorIndex, power) {
+                socket.emit('motorOn', {motorIndex:motorIndex, power:power});
+            };
+    
+            WeDo.setMotorOff = function(motorIndex) {
+                socket.emit('motorOff', {motorIndex:motorIndex});
+            };
+    
+            WeDo.setMotorBrake = function(motorIndex) {
+                socket.emit('motorBrake', {motorIndex:motorIndex});
+            };
+    
+            WeDo.setLED = function(rgb) {
+                socket.emit('setLED', {rgb:rgb});
+            };
+    
+            WeDo.playTone = function(tone, durationMs) {
+                socket.emit('playTone', {tone:tone, ms:durationMs});
+            };
+    
+            WeDo.stopTone = function() {
+                socket.emit('stopTone');
+            };
+    
+            function setHandler(eventName, handler) {
+                if (eventHandlers.hasOwnProperty(eventName)) {
+                    var oldHandler = eventHandlers[eventName];
+                    if (oldHandler) {
+                        socket.removeListener(eventName, oldHandler);
+                    }
+                }
+                if (handler) {
+                    socket.on(eventName, handler);
+                }
+                eventHandlers[eventName] = handler;
+            }
+    
+            // function handler(event) { access event.sensorName and event.sensorValue }
+            WeDo.setSensorHandler = function (handler) {
+                setHandler('sensorChanged', handler);
+            };
+    
+            WeDo.setDeviceWasClosedHandler = function (handler) {
+                // TODO: resolve this ambiguity
+                setHandler('disconnect', handler);
+                setHandler('deviceWasClosed', handler);
+            };
+        }
+
         function disconnect() {
             setTimeout(function () {
                 self.close();
@@ -397,16 +469,27 @@ window.ScratchExtensions = new (function () {
             }, 0);
         }
 
+        this.is_open = function() {
+            return !!dev;
+        };
+
         this.open = function(readyCallback) {
-            ScratchDeviceManager.wedo2_open(self.id, function(d) {
-                dev = d;
-                if (dev) {
+            ScratchDeviceManager.socket_open(self.ext_name, self.ext_type, self.id, function(socket) {
+                if (socket) {
+                    dev = new RawWeDo2(self.id, socket);
                     devices[ext_name] = self;
                     dev.setDeviceWasClosedHandler(disconnect);
                 }
-                if (readyCallback) readyCallback(d ? self : null);
+                else {
+                    dev = null;
+                    disconnect();
+                }
+                if (readyCallback) {
+                    readyCallback(dev ? self : null);
+                }
             });
         };
+
         this.close = function() {
             if (!dev) return;
             dev.close();
@@ -415,9 +498,6 @@ window.ScratchExtensions = new (function () {
 
             checkPolling();
         };
-        this.is_open = function() {
-            return !!dev;
-        };
 
         // The `handler` should be a function like: function handler(event) {...}
         // The `event` will contain properties called `sensorName` and `sensorValue`.
@@ -452,4 +532,84 @@ window.ScratchExtensions = new (function () {
             dev.stopTone();
         };
     }
+
+
+    function BleDevice(id, ext_type, ext_name) {
+        var self = this;
+        this.ext_name = ext_name;
+        this.ext_type = ext_type;
+        this.socket = null;
+
+        this.id = id;
+
+        var onActions = [];
+        var onceActions = [];
+
+        function disconnect() {
+            setTimeout(function () {
+                self.close();
+                handlers[self.ext_name]._deviceRemoved(self);
+            }, 0);
+        }
+
+        this.emit = function(action, data){
+            if(self.socket){
+                self.socket.emit(action, data);
+            }
+            return !!self.socket;
+        };
+
+        this.on = function(action, callback){
+            if(self.is_open()){
+                self.socket.on(action, callback);
+            }
+            else{
+                onActions.push([action, callback]);
+            }
+        };
+
+        this.once = function(action, callback){
+            if(self.is_open()){
+                self.socket.once(action, callback);
+            }
+            else{
+                onceActions.push([action, callback]);
+            }
+        };
+
+        this.open = function(readyCallback) {
+            ScratchDeviceManager.socket_open(self.ext_name, ext_type, self.id, function(s) {
+                self.socket = s; 
+                if (self.socket) {
+                    devices[self.ext_name] = self;
+                    onActions.forEach(function(element){ 
+                        self.socket.on(element[0], element[1]);
+                    });
+                    onceActions.forEach(function(element){
+                        self.socket.once(element[0], element[1]);
+                    });
+
+                    self.socket.on('disconnect', disconnect);
+                    self.socket.on('deviceWasClosed', disconnect);
+
+                }
+                if (readyCallback) readyCallback(self.socket ? self : null);
+            });
+        };
+
+        this.close = function() {
+            if (!self.socket) return;
+            self.socket.close();
+            delete devices[self.ext_name];
+            self.socket = null;
+
+            checkPolling();
+        };
+
+        this.is_open = function() {
+            return !!self.socket;
+        };
+
+    }
+    Devices = {ble: BleDevice, wedo2: WeDo2Device};
 })();
diff --git a/scratch_extensions/scratch_nmh.js b/scratch_extensions/scratch_nmh.js
index 551a56f..fb771bd 100644
--- a/scratch_extensions/scratch_nmh.js
+++ b/scratch_extensions/scratch_nmh.js
@@ -7,7 +7,9 @@ window.ScratchDeviceHost = new (function () {
         return isConnected;
     };
 
-    if (!window.chrome) return;
+    if (!(window.chrome && window.chrome.runtime && window.chrome.runtime.connect)) {
+        return;
+    }
 
     var extensionID = 'clmabinlolakdafkoajkfjjengcdmnpm';
     var callNumber = 0;
diff --git a/scratch_extensions/wedo2Extension.js b/scratch_extensions/wedo2Extension.js
index c5c4c30..32eb1f1 100644
--- a/scratch_extensions/wedo2Extension.js
+++ b/scratch_extensions/wedo2Extension.js
@@ -148,6 +148,9 @@
         return false;
     };
 
+    // Each block must have a unique function name even if the implementation is identical.
+    ext.whenTilted = ext.isTilted;
+
     ext.getTilt = function (tiltDir) {
         var tiltValue;
         switch(tiltDir) {
@@ -332,7 +335,7 @@
             [' ', 'set light color to %n', 'setLED', 50],
             ['w', 'play note %d.note for %n seconds', 'playNote', 60, 0.5],
             ['h', 'when distance %m.lessMore %n', 'whenDistance', strings.COMP_LESS, 50],
-            ['h', 'when tilted %m.tiltDirAny', 'isTilted', strings.TILT_ANY],
+            ['h', 'when tilted %m.tiltDirAny', 'whenTilted', strings.TILT_ANY],
             ['r', 'distance', 'getDistance'],
             ['b', 'tilted %m.tiltDirAny ?', 'isTilted', strings.TILT_ANY],
             ['r', 'tilt angle %m.tiltDir', 'getTilt', strings.TILT_UP]