add getValue() function

utils/equipment.js

@@ -16,6 +16,22 @@ class Equipment {
         this.watch = new Object();
     }
 
+    getValue(valueName, defaultValue) {
+        let valueItemName = this.name + '_' + valueName;
+        let returnValue = defaultValue;
+  
+        if (items[valueItemName] == null) {                             // Return default value if item is missing
+            console.warn('Item ' + valueItemName + ' is missing');
+        } else if (items[valueItemName]['state'] == 'NULL') {           // Return default value if item state is null
+            console.warn('Item ' + valueItemName + ' is unset')
+        } else {                                                        // Return value from item
+            returnValue = items[valueItemName]['state'];
+        }       
+
+        console.debug('Return value ' +  valueName + ' for ' + this.name + ': ' + returnValue);
+        return returnValue;
+    }
+
     gc() {
         console.log('Denitialization of eqipment ' + this.name);
 
@@ -45,7 +61,6 @@ class IrrigationValve extends Equipment {
     }
 }
 
-
 class TowelRadiator extends Equipment {
     constructor(equipmentItem) {
         super(equipmentItem);
@@ -65,3 +80,5 @@ module.exports = {
     IrrigationValve,
     TowelRadiator
 };
+
+