Add more validation:

* ensure group is not empty
* ensure axis group with same name is created twice
* ensure group exists when adding axis

src/ecmcSS1SafetyGroup.cpp

@@ -182,8 +182,7 @@ void ecmcSS1SafetyGroup::validateCfgs() {
   }
 }
 
-void ecmcSS1SafetyGroup::validateAxes() {
-
+void ecmcSS1SafetyGroup::validateAxes() {  
   // Ensure that axis is not linked twice to group 
   for(std::vector<safetyAxis*>::iterator iaxis = axes_.begin(); iaxis != axes_.end(); ++iaxis) {
     int axisLinkedCounter = 0;
@@ -213,11 +212,19 @@ void ecmcSS1SafetyGroup::validateAxes() {
     }    
   }
 
+  int axisCounter = 0;
   // Check axis object exists and valid
   for(std::vector<safetyAxis*>::iterator saxis = axes_.begin(); saxis != axes_.end(); ++saxis) {
     if(!getAxisValid((*saxis)->axisId_)) {
       throw std::runtime_error( "Safety: Ecmc Axis object not valid.");
     }
+    axisCounter++;
+  }
+
+  // do not allow empty group
+  if(axisCounter == 0) {
+    printf("Safety %s: Error, group empty (axis count zero)\n",sName_);
+    throw std::runtime_error( "Safety: Error, empty group not allowed.");
   }
 }