diff --git a/libguh/devicemanager.cpp b/libguh/devicemanager.cpp
index 0ac39161..83e157de 100644
--- a/libguh/devicemanager.cpp
+++ b/libguh/devicemanager.cpp
@@ -172,20 +172,28 @@ QList<DeviceClass> DeviceManager::supportedDevices(const VendorId &vendorId) con
     return ret;
 }
 
-DeviceManager::DeviceError DeviceManager::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const
+QPair<DeviceManager::DeviceError, QString> DeviceManager::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
+    qDebug() << "DeviceManager discoverdevices" << params;
+    // Create a copy of the parameter list because we might modify it (fillig in default values etc)
+    ParamList effectiveParams = params;
     DeviceClass deviceClass = findDeviceClass(deviceClassId);
     if (!deviceClass.isValid()) {
-        return DeviceManager::DeviceErrorDeviceClassNotFound;
+        return qMakePair<DeviceError, QString>(DeviceManager::DeviceErrorDeviceClassNotFound, deviceClass.id().toString());
     }
     if (deviceClass.createMethod() != DeviceClass::CreateMethodDiscovery) {
-        return DeviceManager::DeviceErrorCreationMethodNotSupported;
+        return  qMakePair<DeviceError, QString>(DeviceManager::DeviceErrorCreationMethodNotSupported, "");
+    }
+    QPair<DeviceError, QString> result = verifyParams(deviceClass.discoveryParamTypes(), effectiveParams);
+    if (result.first != DeviceErrorNoError) {
+        qDebug() << "got erorr" << result.first << result.second;
+        return result;
     }
     DevicePlugin *plugin = m_devicePlugins.value(deviceClass.pluginId());
     if (!plugin) {
-        return DeviceManager::DeviceErrorPluginNotFound;
+        return  qMakePair<DeviceError, QString>(DeviceManager::DeviceErrorPluginNotFound, deviceClass.pluginId().toString());
     }
-    return plugin->discoverDevices(deviceClassId, params);
+    return  plugin->discoverDevices(deviceClassId, effectiveParams);
 }
 
 /*! Add a new configured device for the given \l{DeviceClass} and the given parameters.
@@ -207,7 +215,7 @@ DeviceManager::DeviceError DeviceManager::discoverDevices(const DeviceClassId &d
     went wrong during setup. Reasons may be a hardware/network failure, wrong username/password or similar, depending on what the device plugin
     needs to do in order to set up the device.
 */
-QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDevice(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId id)
+QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDevice(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId id)
 {
     DeviceClass deviceClass = findDeviceClass(deviceClassId);
     if (!deviceClass.isValid()) {
@@ -330,8 +338,9 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::confirmPairing(const Q
     return report(DeviceErrorPairingTransactionIdNotFound, pairingTransactionId.toString());
 }
 
-QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDeviceInternal(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId id)
+QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDeviceInternal(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId id)
 {
+    ParamList effectiveParams = params;
     DeviceClass deviceClass = findDeviceClass(deviceClassId);
     if (deviceClass.id().isNull()) {
         qWarning() << "cannot find a device class with id" << deviceClassId;
@@ -343,7 +352,7 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDeviceInt
         return qMakePair<DeviceError, QString>(DeviceErrorCreationMethodNotSupported, "You need to pair this device.");
     }
 
-    QPair<DeviceError, QString> result = verifyParams(deviceClass.paramTypes(), params);
+    QPair<DeviceError, QString> result = verifyParams(deviceClass.paramTypes(), effectiveParams);
     if (result.first != DeviceErrorNoError) {
         return result;
     }
@@ -362,7 +371,7 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::addConfiguredDeviceInt
 
     Device *device = new Device(plugin->pluginId(), id, deviceClassId, this);
     device->setName(deviceClass.name());
-    device->setParams(params);
+    device->setParams(effectiveParams);
 
     QPair<DeviceSetupStatus, QString> status = setupDevice(device);
     switch (status.first) {
@@ -455,6 +464,7 @@ DeviceClass DeviceManager::findDeviceClass(const DeviceClassId &deviceClassId) c
     its \l{DevicePlugin}. Then will dispatch the execution to the \l{DevicePlugin}.*/
 QPair<DeviceManager::DeviceError, QString> DeviceManager::executeAction(const Action &action)
 {
+    Action finalAction = action;
     qDebug() << "should execute action";
     foreach (Device *device, m_configuredDevices) {
         if (action.deviceId() == device->id()) {
@@ -466,10 +476,12 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::executeAction(const Ac
             foreach (const ActionType &actionType, deviceClass.actionTypes()) {
                 qDebug() << "checking" << actionType.id() << action.actionTypeId();
                 if (actionType.id() == action.actionTypeId()) {
-                    QPair<DeviceError, QString> paramCheck = verifyParams(actionType.parameters(), action.params());
+                    ParamList finalParams = action.params();
+                    QPair<DeviceError, QString> paramCheck = verifyParams(actionType.parameters(), finalParams);
                     if (paramCheck.first != DeviceErrorNoError) {
                         return paramCheck;
                     }
+                    finalAction.setParams(finalParams);
 
                     found = true;
                     continue;
@@ -479,7 +491,7 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::executeAction(const Ac
                 return qMakePair<DeviceError, QString>(DeviceErrorActionTypeNotFound, action.actionTypeId().toString());
             }
 
-            return m_devicePlugins.value(device->pluginId())->executeAction(device, action);
+            return m_devicePlugins.value(device->pluginId())->executeAction(device, finalAction);
         }
     }
     return qMakePair<DeviceError, QString>(DeviceErrorDeviceNotFound, action.deviceId().toString());
@@ -858,7 +870,7 @@ QPair<DeviceManager::DeviceSetupStatus,QString> DeviceManager::setupDevice(Devic
     return status;
 }
 
-QPair<DeviceManager::DeviceError, QString> DeviceManager::verifyParams(const QList<ParamType> paramTypes, const QList<Param> &params, bool requireAll)
+QPair<DeviceManager::DeviceError, QString> DeviceManager::verifyParams(const QList<ParamType> paramTypes, ParamList &params, bool requireAll)
 {
     foreach (const Param &param, params) {
         qDebug() << "verifying param" << param.name() << paramTypes;
@@ -877,6 +889,13 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::verifyParams(const QLi
                 found = true;
             }
         }
+
+        // This paramType has a default value... lets fill in that one.
+        if (!paramType.defaultValue().isNull()) {
+            found = true;
+            params.append(Param(paramType.name(), paramType.defaultValue()));
+        }
+
         if (!found) {
             return report(DeviceErrorMissingParameter, QString("Missing parameter: %1").arg(paramType.name()));
         }
@@ -910,6 +929,15 @@ QPair<DeviceManager::DeviceError, QString> DeviceManager::verifyParam(const Para
             return report(DeviceManager::DeviceErrorInvalidParameter, QString("Value out of range for param %1. Got: %2. Min: %3.")
                           .arg(param.name()).arg(param.value().toString()).arg(paramType.minValue().toString()));
         }
+        if (!paramType.allowedValues().isEmpty() && !paramType.allowedValues().contains(param.value())) {
+            QStringList allowedValues;
+            foreach (const QVariant &value, paramType.allowedValues()) {
+                allowedValues.append(value.toString());
+            }
+
+            return report(DeviceManager::DeviceErrorInvalidParameter, QString("Value not in allowed values for param %1. Got: %2. Allowed: %3.")
+                          .arg(param.name()).arg(param.value().toString()).arg(allowedValues.join(",")));
+        }
         return report();
     }
     return report(DeviceErrorInvalidParameter, QString("Parameter name %1 does not match with ParamType name %2")
diff --git a/libguh/devicemanager.h b/libguh/devicemanager.h
index 78e00f42..bba5ea98 100644
--- a/libguh/devicemanager.h
+++ b/libguh/devicemanager.h
@@ -78,10 +78,10 @@ public:
 
     QList<Vendor> supportedVendors() const;
     QList<DeviceClass> supportedDevices(const VendorId &vendorId = VendorId()) const;
-    DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const;
+    QPair<DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params);
 
     QList<Device*> configuredDevices() const;
-    QPair<DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId id = DeviceId::createDeviceId());
+    QPair<DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId id = DeviceId::createDeviceId());
     QPair<DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const DeviceDescriptorId &deviceDescriptorId, const DeviceId &id = DeviceId::createDeviceId());
     QPair<DeviceError, QString> pairDevice(const DeviceClassId &deviceClassId, const QList<Param> &params);
     QPair<DeviceError, QString> pairDevice(const DeviceClassId &deviceClassId, const DeviceDescriptorId &deviceDescriptorId);
@@ -121,9 +121,9 @@ private slots:
     void timerEvent();
 
 private:
-    QPair<DeviceError, QString> addConfiguredDeviceInternal(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId id = DeviceId::createDeviceId());
+    QPair<DeviceError, QString> addConfiguredDeviceInternal(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId id = DeviceId::createDeviceId());
     QPair<DeviceSetupStatus, QString> setupDevice(Device *device);
-    QPair<DeviceError, QString> verifyParams(const QList<ParamType> paramTypes, const QList<Param> &params, bool requireAll = true);
+    QPair<DeviceError, QString> verifyParams(const QList<ParamType> paramTypes, ParamList &params, bool requireAll = true);
     QPair<DeviceError, QString> verifyParam(const QList<ParamType> paramTypes, const Param &param);
     QPair<DeviceError, QString> verifyParam(const ParamType &paramType, const Param &param);
 
diff --git a/libguh/plugin/devicedescriptor.cpp b/libguh/plugin/devicedescriptor.cpp
index 45365596..ebe0efe1 100644
--- a/libguh/plugin/devicedescriptor.cpp
+++ b/libguh/plugin/devicedescriptor.cpp
@@ -76,12 +76,12 @@ void DeviceDescriptor::setDescription(const QString &description)
     m_description = description;
 }
 
-QList<Param> DeviceDescriptor::params() const
+ParamList DeviceDescriptor::params() const
 {
     return m_params;
 }
 
-void DeviceDescriptor::setParams(const QList<Param> &params)
+void DeviceDescriptor::setParams(const ParamList &params)
 {
     m_params = params;
 }
diff --git a/libguh/plugin/devicedescriptor.h b/libguh/plugin/devicedescriptor.h
index 590c6f4a..19d37c58 100644
--- a/libguh/plugin/devicedescriptor.h
+++ b/libguh/plugin/devicedescriptor.h
@@ -42,15 +42,15 @@ public:
     QString description() const;
     void setDescription(const QString &description);
 
-    QList<Param> params() const;
-    void setParams(const QList<Param> &params);
+    ParamList params() const;
+    void setParams(const ParamList &params);
 
 private:
     DeviceDescriptorId m_id;
     DeviceClassId m_deviceClassId;
     QString m_title;
     QString m_description;
-    QList<Param> m_params;
+    ParamList m_params;
 };
 
 Q_DECLARE_METATYPE(DeviceDescriptor)
diff --git a/libguh/plugin/deviceplugin.cpp b/libguh/plugin/deviceplugin.cpp
index f749bc60..7d059946 100644
--- a/libguh/plugin/deviceplugin.cpp
+++ b/libguh/plugin/deviceplugin.cpp
@@ -142,11 +142,11 @@ void DevicePlugin::startMonitoringAutoDevices()
     be an async operation. Return DeviceErrorAsync or DeviceErrorNoError if the discovery
     has been started successfully. Return an appropriate error otherwise.
     Once devices are discovered, emit devicesDiscovered() once. */
-DeviceManager::DeviceError DevicePlugin::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const
+QPair<DeviceManager::DeviceError, QString> DevicePlugin::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
     Q_UNUSED(deviceClassId)
     Q_UNUSED(params)
-    return DeviceManager::DeviceErrorCreationMethodNotSupported;
+    return report(DeviceManager::DeviceErrorCreationMethodNotSupported);
 }
 
 /*! This will be called when a new device is created. The plugin has the chance to do some setup.
diff --git a/libguh/plugin/deviceplugin.h b/libguh/plugin/deviceplugin.h
index a5860dc0..e3bac96a 100644
--- a/libguh/plugin/deviceplugin.h
+++ b/libguh/plugin/deviceplugin.h
@@ -50,7 +50,7 @@ public:
     virtual DeviceManager::HardwareResources requiredHardware() const = 0;
 
     virtual void startMonitoringAutoDevices();
-    virtual DeviceManager::DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const;
+    virtual QPair<DeviceManager::DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params);
 
     virtual QPair<DeviceManager::DeviceSetupStatus, QString> setupDevice(Device *device);
     virtual void deviceRemoved(Device *device);
diff --git a/libguh/types/action.cpp b/libguh/types/action.cpp
index 638e1d7b..f872b3e1 100644
--- a/libguh/types/action.cpp
+++ b/libguh/types/action.cpp
@@ -64,13 +64,13 @@ DeviceId Action::deviceId() const
 }
 
 /*! Returns the parameters for this Action.*/
-QList<Param> Action::params() const
+ParamList Action::params() const
 {
     return m_params;
 }
 
 /*! Set the the parameters for this Action. \a params must match the template in the \l{ActionType} referred by \l{Action::actionTypeId()}*/
-void Action::setParams(const QList<Param> &params)
+void Action::setParams(const ParamList &params)
 {
     m_params = params;
 }
diff --git a/libguh/types/action.h b/libguh/types/action.h
index 9b4eccac..8c4a297c 100644
--- a/libguh/types/action.h
+++ b/libguh/types/action.h
@@ -36,15 +36,15 @@ public:
     ActionTypeId actionTypeId() const;
     DeviceId deviceId() const;
 
-    QList<Param> params() const;
-    void setParams(const QList<Param> &params);
+    ParamList params() const;
+    void setParams(const ParamList &params);
     Param param(const QString &paramName) const;
 
 private:
     ActionId m_id;
     ActionTypeId m_actionTypeId;
     DeviceId m_deviceId;
-    QList<Param> m_params;
+    ParamList m_params;
 };
 
 #endif // ACTION_H
diff --git a/libguh/types/param.cpp b/libguh/types/param.cpp
index 98f8d0ac..d4d472fe 100644
--- a/libguh/types/param.cpp
+++ b/libguh/types/param.cpp
@@ -67,3 +67,34 @@ QDebug operator<<(QDebug dbg, const QList<Param> &params)
 
     return dbg.space();
 }
+
+
+bool ParamList::hasParam(const QString &paramName) const
+{
+    foreach (const Param &param, *this) {
+        if (param.name() == paramName) {
+            return true;
+        }
+    }
+    return false;
+}
+
+QVariant ParamList::paramValue(const QString &paramName) const
+{
+    foreach (const Param &param, *this) {
+        if (param.name() == paramName) {
+            return param.value();
+        }
+    }
+    return QVariant();
+}
+
+void ParamList::setParamValue(const QString &paramName, const QVariant &value)
+{
+    for (int i = 0; i < count(); i++) {
+        if (this->operator [](i).name()  == paramName) {
+            this->operator [](i).setValue(value);
+            return;
+        }
+    }
+}
diff --git a/libguh/types/param.h b/libguh/types/param.h
index 760ba8ef..37f1d542 100644
--- a/libguh/types/param.h
+++ b/libguh/types/param.h
@@ -44,4 +44,12 @@ Q_DECLARE_METATYPE(Param)
 QDebug operator<<(QDebug dbg, const Param &param);
 QDebug operator<<(QDebug dbg, const QList<Param> &params);
 
+class ParamList: public QList<Param>
+{
+public:
+    bool hasParam(const QString &paramName) const;
+    QVariant paramValue(const QString &paramName) const;
+    void setParamValue(const QString &paramName, const QVariant &value);
+};
+
 #endif // PARAM_H
diff --git a/plugins/deviceplugins/mock/devicepluginmock.cpp b/plugins/deviceplugins/mock/devicepluginmock.cpp
index d41a10e5..8d4484db 100644
--- a/plugins/deviceplugins/mock/devicepluginmock.cpp
+++ b/plugins/deviceplugins/mock/devicepluginmock.cpp
@@ -153,6 +153,11 @@ QList<DeviceClass> DevicePluginMock::supportedDevices() const
     DeviceClass deviceClassMockDiscovery(pluginId(), guhVendorId, mockDeviceDiscoveryClassId);
     deviceClassMockDiscovery.setName("Mock Device (Discovery created)");
     deviceClassMockDiscovery.setCreateMethod(DeviceClass::CreateMethodDiscovery);
+    QList<ParamType> paramTypes;
+    ParamType paramType = ParamType("resultCount", QVariant::Int, 2);
+    paramType.setAllowedValues(QList<QVariant>() << 1 << 2);
+    paramTypes.append(paramType);
+    deviceClassMockDiscovery.setDiscoveryParamTypes(paramTypes);
 
     mockParams.clear();
     mockParams.append(portParam);
@@ -207,12 +212,13 @@ DeviceManager::HardwareResources DevicePluginMock::requiredHardware() const
     return DeviceManager::HardwareResourceTimer;
 }
 
-DeviceManager::DeviceError DevicePluginMock::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const
+QPair<DeviceManager::DeviceError, QString> DevicePluginMock::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
     Q_UNUSED(deviceClassId)
     Q_UNUSED(params)
+    m_discoveredDeviceCount = params.paramValue("resultCount").toInt();
     QTimer::singleShot(1000, this, SLOT(emitDevicesDiscovered()));
-    return DeviceManager::DeviceErrorNoError;
+    return report(DeviceManager::DeviceErrorNoError);
 }
 
 QString DevicePluginMock::pluginName() const
@@ -261,7 +267,7 @@ void DevicePluginMock::startMonitoringAutoDevices()
 {
     DeviceDescriptor mockDescriptor(mockDeviceAutoClassId, "Mock Device (Auto created)");
 
-    QList<Param> params;
+    ParamList params;
     Param param("httpport", 4242);
     params.append(param);
     mockDescriptor.setParams(params);
@@ -337,19 +343,23 @@ void DevicePluginMock::emitDevicesDiscovered()
 {
     QList<DeviceDescriptor> deviceDescriptors;
 
-    DeviceDescriptor d1(mockDeviceDiscoveryClassId, "Mock Device (Discovered)");
-    QList<Param> params;
-    Param httpParam("httpport", "7777");
-    params.append(httpParam);
-    d1.setParams(params);
-    deviceDescriptors.append(d1);
+    if (m_discoveredDeviceCount > 0) {
+        DeviceDescriptor d1(mockDeviceDiscoveryClassId, "Mock Device (Discovered)");
+        ParamList params;
+        Param httpParam("httpport", "7777");
+        params.append(httpParam);
+        d1.setParams(params);
+        deviceDescriptors.append(d1);
+    }
 
-    DeviceDescriptor d2(mockDeviceDiscoveryClassId, "Mock Device (Discovered)");
-    params.clear();
-    httpParam.setValue("7778");
-    params.append(httpParam);
-    d2.setParams(params);
-    deviceDescriptors.append(d2);
+    if (m_discoveredDeviceCount > 1) {
+        DeviceDescriptor d2(mockDeviceDiscoveryClassId, "Mock Device (Discovered)");
+        ParamList params;
+        Param httpParam("httpport", "7778");
+        params.append(httpParam);
+        d2.setParams(params);
+        deviceDescriptors.append(d2);
+    }
 
     emit devicesDiscovered(mockDeviceDiscoveryClassId, deviceDescriptors);
 }
diff --git a/plugins/deviceplugins/mock/devicepluginmock.h b/plugins/deviceplugins/mock/devicepluginmock.h
index e7fe37c5..ac35be73 100644
--- a/plugins/deviceplugins/mock/devicepluginmock.h
+++ b/plugins/deviceplugins/mock/devicepluginmock.h
@@ -39,7 +39,7 @@ public:
     QList<Vendor> supportedVendors() const override;
     QList<DeviceClass> supportedDevices() const override;
     DeviceManager::HardwareResources requiredHardware() const override;
-    DeviceManager::DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const override;
+    QPair<DeviceManager::DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params) override;
 
     QString pluginName() const override;
     PluginId pluginId() const override;
@@ -66,6 +66,8 @@ private:
     QHash<Device*, HttpDaemon*> m_daemons;
     QList<Device*> m_asyncSetupDevices;
     QList<QPair<Action, Device*> > m_asyncActions;
+
+    int m_discoveredDeviceCount;
 };
 
 #endif // DEVICEPLUGINMOCK_H
diff --git a/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.cpp b/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.cpp
index c009b38f..9ccf2000 100644
--- a/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.cpp
+++ b/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.cpp
@@ -423,10 +423,12 @@ QList<DeviceClass> DevicePluginOpenweathermap::supportedDevices() const
     return ret;
 }
 
-DeviceManager::DeviceError DevicePluginOpenweathermap::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const
+QPair<DeviceManager::DeviceError, QString> DevicePluginOpenweathermap::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
+    qDebug() << "should discover devices with params:" << params;
     QString location;
     foreach (const Param &param, params) {
+        qDebug() << "### got param:" << param;
         if (param.name() == "location") {
             location = param.value().toString();
         }
@@ -434,10 +436,10 @@ DeviceManager::DeviceError DevicePluginOpenweathermap::discoverDevices(const Dev
 
     if (location.isEmpty()){
         m_openweaher->searchAutodetect();
-        return DeviceManager::DeviceErrorAsync;
+        return report(DeviceManager::DeviceErrorAsync);
     }
     m_openweaher->search(location);
-    return DeviceManager::DeviceErrorAsync;
+    return report(DeviceManager::DeviceErrorAsync);
 }
 
 QPair<DeviceManager::DeviceSetupStatus, QString> DevicePluginOpenweathermap::setupDevice(Device *device)
@@ -482,7 +484,7 @@ void DevicePluginOpenweathermap::searchResultsReady(const QList<QVariantMap> &ci
     QList<DeviceDescriptor> retList;
     foreach (QVariantMap elemant, cityList) {
         DeviceDescriptor descriptor(openweathermapDeviceClassId, elemant.value("name").toString(),elemant.value("country").toString());
-        QList<Param> params;
+        ParamList params;
         Param locationParam("location", elemant.value("name"));
         params.append(locationParam);
         Param countryParam("country", elemant.value("country"));
diff --git a/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.h b/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.h
index 771f58ea..71d4083e 100644
--- a/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.h
+++ b/plugins/deviceplugins/openweathermap/devicepluginopenweathermap.h
@@ -38,7 +38,7 @@ public:
     QList<Vendor> supportedVendors() const override;
     QList<DeviceClass> supportedDevices() const override;
 
-    DeviceManager::DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const override;
+    QPair<DeviceManager::DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params) override;
     QPair<DeviceManager::DeviceSetupStatus, QString> setupDevice(Device *device) override;
     DeviceManager::HardwareResources requiredHardware() const override;
     QPair<DeviceManager::DeviceError, QString> executeAction(Device *device, const Action &action) override;
diff --git a/plugins/deviceplugins/philipshue/devicepluginphilipshue.cpp b/plugins/deviceplugins/philipshue/devicepluginphilipshue.cpp
index 038f9799..b8813fc2 100644
--- a/plugins/deviceplugins/philipshue/devicepluginphilipshue.cpp
+++ b/plugins/deviceplugins/philipshue/devicepluginphilipshue.cpp
@@ -185,10 +185,12 @@ QList<ParamType> DevicePluginPhilipsHue::configurationDescription() const
     return params;
 }
 
-DeviceManager::DeviceError DevicePluginPhilipsHue::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const
+QPair<DeviceManager::DeviceError, QString> DevicePluginPhilipsHue::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
+    Q_UNUSED(deviceClassId)
+    Q_UNUSED(params)
     m_discovery->findBridges(4000);
-    return DeviceManager::DeviceErrorAsync;
+    return report(DeviceManager::DeviceErrorAsync);
 }
 
 QPair<DeviceManager::DeviceSetupStatus, QString> DevicePluginPhilipsHue::setupDevice(Device *device)
@@ -222,7 +224,7 @@ QPair<DeviceManager::DeviceSetupStatus, QString> DevicePluginPhilipsHue::setupDe
     while (!m_unconfiguredLights.isEmpty()) {
         Light *light = m_unconfiguredLights.takeFirst();
         DeviceDescriptor descriptor(hueDeviceClassAutoId, light->name());
-        QList<Param> params;
+        ParamList params;
         params.append(Param("number", light->id()));
         params.append(Param("ip", light->ip().toString()));
         params.append(Param("username", light->username()));
@@ -303,7 +305,7 @@ void DevicePluginPhilipsHue::discoveryDone(const QList<QHostAddress> &bridges)
     QList<DeviceDescriptor> deviceDescriptors;
     foreach (const QHostAddress &bridge, bridges) {
         DeviceDescriptor descriptor(hueDeviceClassId, "Philips Hue bridge", bridge.toString());
-        QList<Param> params;
+        ParamList params;
         Param param("ip", bridge.toString());
         params.append(param);
         Param userParam("username", "guh-" + QUuid::createUuid().toString().remove(QRegExp("[\\{\\}]*")).remove(QRegExp("\\-[0-9a-f\\-]*")));
diff --git a/plugins/deviceplugins/philipshue/devicepluginphilipshue.h b/plugins/deviceplugins/philipshue/devicepluginphilipshue.h
index 49c6c4a8..4da91943 100644
--- a/plugins/deviceplugins/philipshue/devicepluginphilipshue.h
+++ b/plugins/deviceplugins/philipshue/devicepluginphilipshue.h
@@ -46,7 +46,7 @@ public:
     PluginId pluginId() const override;
 
     QList<ParamType> configurationDescription() const override;
-    DeviceManager::DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params) const override;
+    QPair<DeviceManager::DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params) override;
 
     QPair<DeviceManager::DeviceSetupStatus, QString> setupDevice(Device *device) override;
 
diff --git a/server/guhcore.cpp b/server/guhcore.cpp
index 26809643..5b168c8b 100644
--- a/server/guhcore.cpp
+++ b/server/guhcore.cpp
@@ -137,12 +137,12 @@ DeviceClass GuhCore::findDeviceClass(const DeviceClassId &deviceClassId) const
     return m_deviceManager->findDeviceClass(deviceClassId);
 }
 
-DeviceManager::DeviceError GuhCore::discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params)
+QPair<DeviceManager::DeviceError, QString> GuhCore::discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params)
 {
     return m_deviceManager->discoverDevices(deviceClassId, params);
 }
 
-QPair<DeviceManager::DeviceError, QString> GuhCore::addConfiguredDevice(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId &newId)
+QPair<DeviceManager::DeviceError, QString> GuhCore::addConfiguredDevice(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId &newId)
 {
     return m_deviceManager->addConfiguredDevice(deviceClassId, params, newId);
 }
diff --git a/server/guhcore.h b/server/guhcore.h
index 24146dcf..a4433ed3 100644
--- a/server/guhcore.h
+++ b/server/guhcore.h
@@ -49,8 +49,8 @@ public:
     QList<Vendor> supportedVendors() const;
     QList<DeviceClass> supportedDevices(const VendorId &vendorId = VendorId()) const;
     DeviceClass findDeviceClass(const DeviceClassId &deviceClassId) const;
-    DeviceManager::DeviceError discoverDevices(const DeviceClassId &deviceClassId, const QList<Param> &params);
-    QPair<DeviceManager::DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const QList<Param> &params, const DeviceId &newId);
+    QPair<DeviceManager::DeviceError, QString> discoverDevices(const DeviceClassId &deviceClassId, const ParamList &params);
+    QPair<DeviceManager::DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const ParamList &params, const DeviceId &newId);
     QPair<DeviceManager::DeviceError, QString> addConfiguredDevice(const DeviceClassId &deviceClassId, const DeviceDescriptorId &deviceDescriptorId, const DeviceId &newId);
     QList<Device*> configuredDevices() const;
     Device *findConfiguredDevice(const DeviceId &deviceId) const;
diff --git a/server/jsonrpc/actionhandler.cpp b/server/jsonrpc/actionhandler.cpp
index 7d448240..bb8c76d2 100644
--- a/server/jsonrpc/actionhandler.cpp
+++ b/server/jsonrpc/actionhandler.cpp
@@ -59,7 +59,7 @@ JsonReply* ActionHandler::ExecuteAction(const QVariantMap &params)
 
     DeviceId deviceId(params.value("deviceId").toString());
     ActionTypeId actionTypeId(params.value("actionTypeId").toString());
-    QList<Param> actionParams = JsonTypes::unpackParams(params.value("params").toList());
+    ParamList actionParams = JsonTypes::unpackParams(params.value("params").toList());
 
     Action action(actionTypeId, deviceId);
     action.setParams(actionParams);
diff --git a/server/jsonrpc/devicehandler.cpp b/server/jsonrpc/devicehandler.cpp
index 50625dd2..4258de61 100644
--- a/server/jsonrpc/devicehandler.cpp
+++ b/server/jsonrpc/devicehandler.cpp
@@ -249,14 +249,10 @@ JsonReply *DeviceHandler::GetDiscoveredDevices(const QVariantMap &params) const
 
     DeviceClassId deviceClassId = DeviceClassId(params.value("deviceClassId").toString());
 
-    QList<Param> discoveryParams;
-    foreach (const QVariant &discoveryParam, params.value("discoveryParams").toList()) {
-        Param dp(discoveryParam.toMap().keys().first(), discoveryParam.toMap().values().first());
-        discoveryParams.append(dp);
-    }
+    ParamList discoveryParams = JsonTypes::unpackParams(params.value("discoveryParams").toList());
 
-    DeviceManager::DeviceError status = GuhCore::instance()->discoverDevices(deviceClassId, discoveryParams);
-    switch (status) {
+    QPair<DeviceManager::DeviceError, QString> status = GuhCore::instance()->discoverDevices(deviceClassId, discoveryParams);
+    switch (status.first) {
     case DeviceManager::DeviceErrorAsync:
     case DeviceManager::DeviceErrorNoError: {
         JsonReply *reply = createAsyncReply("GetDiscoveredDevices");
@@ -264,7 +260,7 @@ JsonReply *DeviceHandler::GetDiscoveredDevices(const QVariantMap &params) const
         return reply;
     }
     case DeviceManager::DeviceErrorDeviceClassNotFound:
-        returns.insert("errorMessage", "Cannot discover devices. Unknown DeviceClassId.");
+        returns.insert("errorMessage", QString("Cannot discover devices. Unknown DeviceClassId: %1").arg(status.second));
         break;
     case DeviceManager::DeviceErrorPluginNotFound:
         returns.insert("errorMessage", "Cannot discover devices. Plugin for DeviceClass not found.");
@@ -272,8 +268,11 @@ JsonReply *DeviceHandler::GetDiscoveredDevices(const QVariantMap &params) const
     case DeviceManager::DeviceErrorCreationMethodNotSupported:
         returns.insert("errorMessage", "This device can't be discovered.");
         break;
+    case DeviceManager::DeviceErrorMissingParameter:
+        returns.insert("errorMessage", QString("Missing parameter: %1").arg(status.second));
+        break;
     default:
-        returns.insert("errorMessage", QString("Unknown error %1").arg(status));
+        returns.insert("errorMessage", QString("Unknown error %1 %2").arg(status.first).arg(status.second));
     }
 
     returns.insert("success", false);
@@ -330,11 +329,7 @@ JsonReply* DeviceHandler::SetPluginConfiguration(const QVariantMap &params)
 {
     QVariantMap returns;
     PluginId pluginId = PluginId(params.value("pluginId").toString());
-    QList<Param> pluginParams;
-    foreach (const QVariant &param, params.value("configuration").toList()) {
-        qDebug() << "got param" << param;
-        pluginParams.append(JsonTypes::unpackParam(param.toMap()));
-    }
+    ParamList pluginParams = JsonTypes::unpackParams(params.value("configuration").toList());
     QPair<DeviceManager::DeviceError, QString> result = GuhCore::instance()->setPluginConfig(pluginId, pluginParams);
     returns.insert("success", result.first == DeviceManager::DeviceErrorNoError);
     returns.insert("errorMessage", result.second);
@@ -344,13 +339,7 @@ JsonReply* DeviceHandler::SetPluginConfiguration(const QVariantMap &params)
 JsonReply* DeviceHandler::AddConfiguredDevice(const QVariantMap &params)
 {
     DeviceClassId deviceClass(params.value("deviceClassId").toString());
-    QList<Param> deviceParams;
-    foreach (const QVariant &paramVariant, params.value("deviceParams").toList()) {
-         Param param(paramVariant.toMap().value("name").toString());
-         param.setValue(paramVariant.toMap().value("value"));
-         deviceParams.append(param);
-    }
-
+    ParamList deviceParams = JsonTypes::unpackParams(params.value("deviceParams").toList());
     DeviceDescriptorId deviceDescriptorId(params.value("deviceDescriptorId").toString());
     DeviceId newDeviceId = DeviceId::createDeviceId();
     QPair<DeviceManager::DeviceError, QString> status;
@@ -410,12 +399,7 @@ JsonReply *DeviceHandler::PairDevice(const QVariantMap &params)
         DeviceDescriptorId deviceDescriptorId(params.value("deviceDescriptorId").toString());
         status = GuhCore::instance()->pairDevice(deviceClassId, deviceDescriptorId);
     } else {
-        QList<Param> deviceParams;
-        foreach (const QString &paramName, params.value("deviceParams").toMap().keys()) {
-             Param param(paramName);
-             param.setValue(params.value("deviceParams").toMap().value(paramName));
-             deviceParams.append(param);
-        }
+        ParamList deviceParams = JsonTypes::unpackParams(params.value("deviceParams").toList());
         status = GuhCore::instance()->pairDevice(deviceClassId, deviceParams);
     }
 
diff --git a/server/jsonrpc/jsonrpcserver.cpp b/server/jsonrpc/jsonrpcserver.cpp
index 883c0627..4d3d5c57 100644
--- a/server/jsonrpc/jsonrpcserver.cpp
+++ b/server/jsonrpc/jsonrpcserver.cpp
@@ -42,7 +42,7 @@
 #include <QJsonDocument>
 #include <QStringList>
 
-#define JSON_PROTOCOL_VERSION 3
+#define JSON_PROTOCOL_VERSION 4
 
 JsonRPCServer::JsonRPCServer(QObject *parent):
     JsonHandler(parent),
diff --git a/server/jsonrpc/jsontypes.cpp b/server/jsonrpc/jsontypes.cpp
index 9a95bb40..589bcc8e 100644
--- a/server/jsonrpc/jsontypes.cpp
+++ b/server/jsonrpc/jsontypes.cpp
@@ -444,9 +444,9 @@ Param JsonTypes::unpackParam(const QVariantMap &paramMap)
     return Param(name, value);
 }
 
-QList<Param> JsonTypes::unpackParams(const QVariantList &paramList)
+ParamList JsonTypes::unpackParams(const QVariantList &paramList)
 {
-    QList<Param> params;
+    ParamList params;
     foreach (const QVariant &paramVariant, paramList) {
         qDebug() << "unpacking param" << paramVariant;
         params.append(unpackParam(paramVariant.toMap()));
diff --git a/server/jsonrpc/jsontypes.h b/server/jsonrpc/jsontypes.h
index 6b04e69e..9cce0109 100644
--- a/server/jsonrpc/jsontypes.h
+++ b/server/jsonrpc/jsontypes.h
@@ -108,7 +108,7 @@ public:
     static QVariantMap packRule(const Rule &rule);
 
     static Param unpackParam(const QVariantMap &paramMap);
-    static QList<Param> unpackParams(const QVariantList &paramList);
+    static ParamList unpackParams(const QVariantList &paramList);
     static ParamDescriptor unpackParamDescriptor(const QVariantMap &paramDescriptorMap);
     static QList<ParamDescriptor> unpackParamDescriptors(const QVariantList &paramDescriptorList);
     static EventDescriptor unpackEventDescriptor(const QVariantMap &eventDescriptorMap);
diff --git a/server/ruleengine.cpp b/server/ruleengine.cpp
index 570a2d23..4790945a 100644
--- a/server/ruleengine.cpp
+++ b/server/ruleengine.cpp
@@ -114,7 +114,7 @@ RuleEngine::RuleEngine(QObject *parent) :
         foreach (const QString &actionIdString, settings.childGroups()) {
             settings.beginGroup(actionIdString);
             Action action = Action(ActionTypeId(settings.value("actionTypeId").toString()), DeviceId(settings.value("deviceId").toString()));
-            QList<Param> params;
+            ParamList params;
             foreach (QString paramNameString, settings.childGroups()) {
                 if (paramNameString.startsWith("Param-")) {
                     settings.beginGroup(paramNameString);
diff --git a/tests/auto/api.json b/tests/auto/api.json
index 774e6966..aff12c91 100644
--- a/tests/auto/api.json
+++ b/tests/auto/api.json
@@ -1,4 +1,4 @@
-3
+4
 {
     "methods": {
         "Actions.ExecuteAction": {
@@ -419,6 +419,9 @@
         },
         "ParamType": {
             "name": "string",
+            "o:allowedValues": [
+                "variant"
+            ],
             "o:defaultValue": "variant",
             "o:maxValue": "variant",
             "o:minValue": "variant",
diff --git a/tests/auto/devices/testdevices.cpp b/tests/auto/devices/testdevices.cpp
index b82624c0..ac625d6c 100644
--- a/tests/auto/devices/testdevices.cpp
+++ b/tests/auto/devices/testdevices.cpp
@@ -328,10 +328,18 @@ void TestDevices::discoverDevices_data()
     QTest::addColumn<DeviceClassId>("deviceClassId");
     QTest::addColumn<int>("resultCount");
     QTest::addColumn<bool>("success");
+    QTest::addColumn<QVariantList>("discoveryParams");
 
-    QTest::newRow("valid deviceClassId") << mockDeviceDiscoveryClassId << 2 << true;
-    QTest::newRow("invalid deviceClassId") << DeviceClassId::createDeviceClassId() << 0 << false;
-    QTest::newRow("CreateMethodUser deviceClassId") << mockDeviceClassId << 0 << false;
+    QVariantList discoveryParams;
+    QVariantMap resultCountParam;
+    resultCountParam.insert("name", "resultCount");
+    resultCountParam.insert("value", 1);
+    discoveryParams.append(resultCountParam);
+
+    QTest::newRow("valid deviceClassId") << mockDeviceDiscoveryClassId << 2 << true << QVariantList();
+    QTest::newRow("valid deviceClassId with params") << mockDeviceDiscoveryClassId << 1 << true << discoveryParams;
+    QTest::newRow("invalid deviceClassId") << DeviceClassId::createDeviceClassId() << 0 << false << QVariantList();
+    QTest::newRow("CreateMethodUser deviceClassId") << mockDeviceClassId << 0 << false << QVariantList();
 }
 
 void TestDevices::discoverDevices()
@@ -339,9 +347,11 @@ void TestDevices::discoverDevices()
     QFETCH(DeviceClassId, deviceClassId);
     QFETCH(int, resultCount);
     QFETCH(bool, success);
+    QFETCH(QVariantList, discoveryParams);
 
     QVariantMap params;
     params.insert("deviceClassId", deviceClassId);
+    params.insert("discoveryParams", discoveryParams);
     QVariant response = injectAndWait("Devices.GetDiscoveredDevices", params);
 
     verifySuccess(response, success);
@@ -353,6 +363,8 @@ void TestDevices::discoverDevices()
     if (success) {
         DeviceDescriptorId descriptorId = DeviceDescriptorId(response.toMap().value("params").toMap().value("deviceDescriptors").toList().first().toMap().value("id").toString());
 
+        params.clear();
+        params.insert("deviceClassId", deviceClassId);
         params.insert("deviceDescriptorId", descriptorId.toString());
         response = injectAndWait("Devices.AddConfiguredDevice", params);