diff --git a/src/components/widget-gauge.js b/src/components/widget-gauge.js
index 9493c6b..5fc4153 100644
--- a/src/components/widget-gauge.js
+++ b/src/components/widget-gauge.js
@@ -180,7 +180,7 @@ class WidgetGauge extends Component {
 
     if (this.props.simulation) {
       const simulationModel = this.props.simulation.models.filter((model) => model.simulator.node === this.props.widget.simulator.node && model.simulator.simulator === this.props.widget.simulator.simulator)[0];
-      signalType = (simulationModel != null && simulationModel.length > 0) ? simulationModel.mapping[this.props.widget.signal].type : '';
+      signalType = (simulationModel != null && simulationModel.length > 0 && this.props.widget.signal < simulationModel.length) ? simulationModel.mapping[this.props.widget.signal].type : '';
     }
 
     return (
diff --git a/src/components/widget-value.js b/src/components/widget-value.js
index 1f5e6b4..4744d22 100644
--- a/src/components/widget-value.js
+++ b/src/components/widget-value.js
@@ -46,7 +46,10 @@ class WidgetValue extends Component {
 
     if (nextProps.simulation) {
       const simulationModel = nextProps.simulation.models.find(model => model.simulator.node === node && model.simulator.simulator === simulator);
-      unit = simulationModel.mapping[nextProps.widget.signal].type;
+      
+      if (nextProps.widget.signal < simulationModel.mapping.length) {
+        unit = simulationModel.mapping[nextProps.widget.signal].type;
+      }
     }
     
     // check if value has changed