diff --git a/src/ecmcSS1SafetyGroup.cpp b/src/ecmcSS1SafetyGroup.cpp
index eac5317..d085aa4 100644
--- a/src/ecmcSS1SafetyGroup.cpp
+++ b/src/ecmcSS1SafetyGroup.cpp
@@ -290,6 +290,10 @@ void ecmcSS1SafetyGroup::connectToDataSources() {
     throw std::runtime_error( "Safety: EtherCAT entry for rampdown I/O NULL.");
   }
 
+  if(bitRampDown_ >= ecEntryRampDown_->getBits()) {
+    throw std::runtime_error( "Safety: Bit out of range for rampdown ethercat entry.");
+  }
+
   // standstill
   slave = ecMaster_->findSlave(slaveIdStandStill_);
   if(!slave) {
@@ -301,6 +305,9 @@ void ecmcSS1SafetyGroup::connectToDataSources() {
     throw std::runtime_error( "Safety: EtherCAT entry for standstill I/O NULL.");
   };
 
+  if(bitStandStill_ >= ecEntryStandstill_->getBits()) {
+    throw std::runtime_error( "Safety: Bit out of range for standstill ethercat entry.");
+  }
 
   // Limit velo
   if( limitMaxVeloEnable_ ) {
@@ -313,6 +320,10 @@ void ecmcSS1SafetyGroup::connectToDataSources() {
     if(!ecEntryLimitVelo_) {
       throw std::runtime_error( "Safety: EtherCAT entry for limit velo I/O NULL.");
     };
+
+    if(bitLimitVelo_ >= ecEntryLimitVelo_->getBits()) {
+      throw std::runtime_error( "Safety: Bit out of range for limit velo ethercat entry.");
+    }
   }
   dataSourcesLinked_ = 1;