Deal with clock singal

additional_nodes/recirculation-pump.js

@@ -24,6 +24,8 @@ module.exports = function(RED) {
 
                     send([msg_F1, msg_F2]);
                     break;
+                case "clock":
+                    break;
                 default:
                     console.log("Unknown topic: " + msg.topic);
             }

additional_nodes/settling-basin.js

@@ -41,6 +41,8 @@ module.exports = function(RED) {
 
                     send([msg_F1, msg_F2]);
                     break;
+                case "clock":
+                    break;
                 default:
                     console.log("Unknown topic: " + msg.topic);
             }