diff --git a/src/ATBAPP/ATBDeviceControllerPlugin.cpp b/src/ATBAPP/ATBDeviceControllerPlugin.cpp
index 4e98404..883b9d6 100644
--- a/src/ATBAPP/ATBDeviceControllerPlugin.cpp
+++ b/src/ATBAPP/ATBDeviceControllerPlugin.cpp
@@ -224,7 +224,33 @@ void ATBDeviceControllerPlugin::requestStopCashInput()
 void ATBDeviceControllerPlugin::cashCollect()
 {
     hw->vend_success();
-    this->currentCashState = CASH_STATE::CACHE_EMPTY;
+
+    // inserted amount
+    uint32_t amountInt = this->hw->getInsertedAmount();
+    QString amountString = QString::number(amountInt);
+
+    // inserted coins
+    uint32_t amountCoinsInt = CashUtils::getAmountOfInsertedCoins(this->hw);
+    QString amountCoinsString = QString::number(amountCoinsInt);
+
+    // inserted notes
+    uint32_t amountNotesInt = CashUtils::getAmountOfInsertedNotes(this->hw);
+    QString amountNotesString = QString::number(amountNotesInt);
+
+
+    if (this->coinProcessor() == nsDeviceControllerInterface::COIN_PROCESSOR::CHANGER) {
+        QTimer::singleShot(1000, this, &ATBDeviceControllerPlugin::onCashChangerState);
+    }
+    else {
+        emit this->cashPaymentFinished(nsDeviceControllerInterface::RESULT_STATE::SUCCESS,
+                                  amountString,
+                                  amountCoinsString,        // coins
+                                  amountNotesString,        // notes
+                                  0,                        // proposed change
+                                  "",
+                                  "");
+        this->currentCashState = CASH_STATE::CACHE_EMPTY;
+    }
 }
 
 void ATBDeviceControllerPlugin::cashAbort()
@@ -1002,13 +1028,34 @@ void ATBDeviceControllerPlugin::onCashPayStopedSuccess()
     QString amountNotesString = QString::number(amountNotesInt);
 
     // amount due to change
-    uint32_t amountDueToChangeInt = this->cashStartAmountInt - amountInt;
+    uint32_t amountDueToChangeInt;
+    if (amountInt > this->cashStartAmountInt) {
+        amountDueToChangeInt = amountInt - this->cashStartAmountInt;
+    }
+    else {
+        amountDueToChangeInt = 0;
+    }
     QString amountDueToChangeString = QString::number(amountDueToChangeInt);
 
 
     // DEBUG
-    qCritical() << "      insertedAmount (int) = " << amountInt;
-    qCritical() << "            insertedAmount = " << amountString;
+    qCritical() << "---------------------------------------------------------";
+    qCritical() << "ATBDeviceControllerPlugin::onCashPayStopedSuccess()";
+    qCritical() << "";
+    qCritical() << "                         amountInt: " << amountInt;
+    qCritical() << "                      amountString: " << amountString;
+    qCritical() << "";
+    qCritical() << "                    amountNotesInt: " << amountNotesInt;
+    qCritical() << "                 amountNotesString: " << amountNotesString;
+    qCritical() << "";
+    qCritical() << "                    amountCoinsInt: " << amountCoinsInt;
+    qCritical() << "                 amountCoinsString: " << amountCoinsString;
+    qCritical() << "";
+    qCritical() << "          this->cashStartAmountInt: " << this->cashStartAmountInt;
+    qCritical() << "              amountDueToChangeInt: " << amountDueToChangeInt;
+    qCritical() << "           amountDueToChangeString: " << amountDueToChangeString;
+    qCritical() << "---------------------------------------------------------";
+
 
     emit this->cashInputFinished(nsDeviceControllerInterface::RESULT_STATE::SUCCESS,
                               amountString,
@@ -1019,6 +1066,141 @@ void ATBDeviceControllerPlugin::onCashPayStopedSuccess()
                               "");
 }
 
+void ATBDeviceControllerPlugin::onCashChangerState()
+{
+    uint32_t amountThatCouldNotBeChangedInt;
+
+    static int changerStateRequestCounter = 0;
+    static uint8_t lastChangerResult = 0;
+
+
+    // inserted amount
+    uint32_t amountInt = this->hw->getInsertedAmount();
+    QString amountString = QString::number(amountInt);
+
+    // inserted coins
+    uint32_t amountCoinsInt = CashUtils::getAmountOfInsertedCoins(this->hw);
+    QString amountCoinsString = QString::number(amountCoinsInt);
+
+    // inserted notes
+    uint32_t amountNotesInt = CashUtils::getAmountOfInsertedNotes(this->hw);
+    QString amountNotesString = QString::number(amountNotesInt);
+
+    // amount due to change
+    uint32_t amountCoinsChangedInt;
+    if (amountInt > this->cashStartAmountInt) {
+        amountCoinsChangedInt = amountInt - this->cashStartAmountInt;
+    }
+    else {
+        amountCoinsChangedInt = 0;
+    }
+    QString amountCoinsChangedString = QString::number(amountCoinsChangedInt);
+
+
+    // get changer state ------------------------------------------------
+    // Note: 'returnedAmount'-parameter is missleading here!
+    // 'returnedAmount' is the amount which could not be changed!
+
+    lastChangerResult = hw->changer_getChangeResult(&amountThatCouldNotBeChangedInt);
+
+    // DEBUG
+    qCritical() << "---------------------------------------------------------";
+    qCritical() << "ATBDeviceControllerPlugin::onCashChangerState()";
+    qCritical() << "        changerStateRequestCounter: " << changerStateRequestCounter;
+    qCritical() << "                 lastChangerResult: " << lastChangerResult;
+    qCritical() << "    amountThatCouldNotBeChangedInt: " << amountThatCouldNotBeChangedInt;
+    qCritical() << "";
+    qCritical() << "                         amountInt: " << amountInt;
+    qCritical() << "                      amountString: " << amountString;
+    qCritical() << "";
+    qCritical() << "                    amountCoinsInt: " << amountCoinsInt;
+    qCritical() << "                 amountCoinsString: " << amountCoinsString;
+    qCritical() << "";
+    qCritical() << "                    amountNotesInt: " << amountNotesInt;
+    qCritical() << "                 amountNotesString: " << amountNotesString;
+    qCritical() << "";
+    qCritical() << "          this->cashStartAmountInt: " << this->cashStartAmountInt;
+    qCritical() << "             amountCoinsChangedInt: " << amountCoinsChangedInt;
+    qCritical() << "          amountCoinsChangedString: " << amountCoinsChangedString;
+    qCritical() << "---------------------------------------------------------";
+
+    if (lastChangerResult == 1) { // change is returned
+
+
+        QString amountCoinsChangedString = QString::number(amountCoinsChangedInt);
+
+        emit this->cashPaymentFinished(nsDeviceControllerInterface::RESULT_STATE::SUCCESS,
+                                  amountString,
+                                  amountCoinsString,        // coins
+                                  amountNotesString,        // notes
+                                  amountCoinsChangedString, // change
+                                  "",
+                                  "");
+        changerStateRequestCounter = 0;
+        lastChangerResult = 0;
+        return;
+    }
+    else
+    if (lastChangerResult == 0) { // not yet started
+        qCritical() << "ATBDeviceControllerPlugin::onCashChangerState(): ERROR: change not yet started: amount due to return: " << amountCoinsChangedString;
+    }
+    else
+    if (lastChangerResult == 2) { // only partial return
+        qCritical() << "ATBDeviceControllerPlugin::onCashChangerState(): ERROR: only partial return: amount due to return: " << amountCoinsChangedString;
+    }
+    else
+    if (lastChangerResult == 3) { // no return possible
+        qCritical() << "ATBDeviceControllerPlugin::onCashChangerState(): ERROR: no return possible: amount due to return: " << amountCoinsChangedString;
+    }
+    else {
+        qCritical() << "ATBDeviceControllerPlugin::onCashChangerState(): ERROR: invalid changerState (" << lastChangerResult << ")";
+    }
+
+
+    // handle timeout ------------------------------------------------
+    if (changerStateRequestCounter > 15) {
+        QString errorCode;
+        QString errorDescription;
+        switch (lastChangerResult) {
+        case 0:  // not yet started
+            errorCode = "DC::CHANGER::START";
+            errorDescription = "Changer does not start";
+            break;
+        case 1:  // amount returned
+            // This error should not occur!
+            errorCode = "DC::CHANGER::INVALID";
+            errorDescription = "Changer returned amount";
+            break;
+        case 2:  // only partial return
+            errorCode = "DC::CHANGER::CHANGE";
+            errorDescription = "Changer does only partial return";
+            break;
+        case 3:  // no return possible
+            errorCode = "DC::CHANGER::CHANGE_NOT_POSSIBLE";
+            errorDescription = "Changing not possible";
+            break;
+        default:
+
+            break;
+        }
+        emit this->cashPaymentFinished(nsDeviceControllerInterface::RESULT_STATE::ERROR_BACKEND,
+                                  amountString,
+                                  amountCoinsString,
+                                  amountNotesString,
+                                  0,
+                                  errorCode,
+                                  errorDescription);
+        changerStateRequestCounter = 0;
+        lastChangerResult = 0;
+        return;
+    }
+
+    // restart changer check:
+    changerStateRequestCounter++;
+    QTimer::singleShot(1000, this, &ATBDeviceControllerPlugin::onCashChangerState);
+}
+
+
 
 
 /**
diff --git a/src/ATBAPP/ATBDeviceControllerPlugin.h b/src/ATBAPP/ATBDeviceControllerPlugin.h
index 48709f6..e3f39f6 100644
--- a/src/ATBAPP/ATBDeviceControllerPlugin.h
+++ b/src/ATBAPP/ATBDeviceControllerPlugin.h
@@ -151,6 +151,7 @@ private slots:
    void onCashPayStopByEscrow();
    void onCashPayStopByError();
    void onCashPayStopByTimeout();
+   void onCashChangerState();
 
    // doors and hardware contacts
    void onServiceDoorOpened();