Fallback to miIO-call if developer API does not respond

lib/devices/gateway/subdevice.js

@@ -168,11 +168,32 @@ module.exports = Thing.type(Parent => class SubDevice extends Parent {
 				resolve(this.getProperties(props));
 			};
 
-			// Reject this promise in 5 seconds
+			/*
+			 * Fallback behavior, use a regular call if properties have not
+			 * been resolved in a second.
+			 */
 			setTimeout(() => {
-				this._currentRead = null;
-				reject(new Error('Timeout while waiting for sub-device properties'));
-			}, 5000);
+				this.debug('Read via DEV timed out, using fallback API');
+				this._parent.call('get_device_prop_exp', [ [ 'lumi.' + this.internalId, ...this._propertiesToMonitor ]])
+					.then(result => {
+						for(let i=0; i<result[0].length; i++) {
+							let name = this._propertiesToMonitor[i];
+							const def = this._propertyDefinitions[name];
+							let value = result[0][i];
+
+							name = def.name || name;
+							value = def.mapper(value);
+
+							this.setProperty(name, value);
+						}
+
+						this._currentRead.resolve();
+					})
+					.catch(err => {
+						this._currentRead = null;
+						reject(err);
+					});
+			}, 1000);
 		});
 
 		return this._currentRead.promise;