diff --git a/api/blueweather.php b/api/blueweather.php
index 0744b77..1aa48cb 100755
--- a/api/blueweather.php
+++ b/api/blueweather.php
@@ -139,8 +139,12 @@ class BlueWeather
      * 
      * @param int   $locId   id of the location to return data of
      * @param mixed $range   contains 'from' and 'to' as unix timestamps
-     * @param int   $maxVals maximum measvals to be transmitted; if more are 
-     *                       present in the timespan, the avarage will be calculated
+     * @param mixed $maxVals array containing:
+     *                       'count': maximum measvals to be transmitted
+     *                       'mode': 
+     *                       - 'newest': will return the newest <maxVals> values
+     *                       - 'oldest': will return the oldest <maxVals> values
+     *                       - 'avg'   : <maxVals> sub avarages will be calculated
      * 
      * @return mixed object with all information about the location (see docs)
      */
@@ -150,7 +154,6 @@ class BlueWeather
         $locId = $this->_con->real_escape_string($locId);
         $range["from"] = $this->_con->real_escape_string($range["from"]);
         $range["to"] = $this->_con->real_escape_string($range["to"]);
-        $maxVals = $this->_con->real_escape_string($maxVals);
 
         $sql = "SELECT * FROM `locations`
         WHERE`id`=$locId";
@@ -162,6 +165,10 @@ class BlueWeather
         if (!isset($range['from']) || $range['from'] === "") {
             $range['from'] = time() - 24 * 60 * 60;
         }
+
+        if ($range['from'] < 0) {
+            $range['from'] = time() + $range['from'];
+        }
     
         if (!isset($range['to']) || $range['to'] === "") {
             $range['to'] = time();
@@ -198,7 +205,7 @@ class BlueWeather
     
         $result = $this->_con->query($sql);
     
-        //loop through the returned data
+        // get all necessaray valuetypes
         while ($row = $result->fetch_assoc()) {
             foreach ($sensors as $sensor) {
                 if ($sensor['valuetypeid'] == $row['id']) {
@@ -208,67 +215,86 @@ class BlueWeather
             }
         }
     
-        if (isset($maxVals) && $maxVals > 0) {
+        if (isset($maxVals) && isset($maxVals['count']) && isset($maxVals['mode'])) {
             // build the new measvalues array with respect to maxVals for each sensor
     
             $finalMeasvals = array();
     
             foreach ($sensors as $sensor) {
                 
-                // get all measvalues of the current sensor
                 $rawMeasvalsOfThisSensor = array();
                 $finalMeasvalsOfThisSensor = array();
     
+                // get all measvalues of the current sensor
                 foreach ($measvalues as $measvalue) {
                     if ($measvalue["sensorid"] === $sensor["id"]) {
                         array_push($rawMeasvalsOfThisSensor, $measvalue);
                     }
                 }
 
-                if (count($rawMeasvalsOfThisSensor) <= $maxVals) {
+                if (count($rawMeasvalsOfThisSensor) <= $maxVals['count']) {
+                    // measvls don't exceed maxVals -> nothng needs to be done
                     $finalMeasvals = array_merge(
                         $finalMeasvals, $rawMeasvalsOfThisSensor
                     );
                     continue;
                 }
     
-                // always sum up the same amount of values to get a new array
-                // which doesn't have more than $maxVals values
-                $countOfValuesForAvarage = intval(
-                    round(count($rawMeasvalsOfThisSensor) / $maxVals, 0)
-                );
-    
-                $takenValuesForNextSum = 0;
-                $tmpMeasvalueSum = 0;
-                $tmpTimestampSum = 0;
-    
-                for ($i = 0; $i < count($rawMeasvalsOfThisSensor); $i++) {
-                    // loop through all measvals of the sensor
-                    $measvalue = $rawMeasvalsOfThisSensor[$i];
-                    
-                    if ($measvalue["sensorid"] === $sensor["id"]) {
-                        $tmpMeasvalueSum += $measvalue["measvalue"];
-                        $tmpTimestampSum += $measvalue["timestamp"];
-                        $takenValuesForNextSum += 1;
-                    }
-                    if ($takenValuesForNextSum === $countOfValuesForAvarage || $i === count($rawMeasvalsOfThisSensor) - 1) {
-                        array_push(
-                            $finalMeasvalsOfThisSensor,
-                            array(
-                                "measvalue" => round(
-                                    $tmpMeasvalueSum / $takenValuesForNextSum, 2
-                                ),
-                                "timestamp" => round(
-                                    $tmpTimestampSum / $takenValuesForNextSum, 0
-                                ),
-                                "sensorid" => $sensor["id"]
-                            )
-                        );
-    
-                        $takenValuesForNextSum = 0;
-                        $tmpMeasvalueSum = 0;
-                        $tmpTimestampSum = 0;
+                switch($maxVals['mode']) {
+                case "newest": 
+                    $finalMeasvalsOfThisSensor = array_slice(
+                        $rawMeasvalsOfThisSensor, 
+                        count($rawMeasvalsOfThisSensor) - $maxVals['count'],
+                        count($rawMeasvalsOfThisSensor)
+                    );
+                    break;
+                case "oldest":
+                    $finalMeasvalsOfThisSensor = array_slice(
+                        $rawMeasvalsOfThisSensor, 0, $maxVals['count']
+                    );
+                    break;
+                case "avg":
+                    // always sum up the same amount of values to get a new array
+                    // which doesn't have more than $maxVals values
+                    $countOfValuesForAvarage = intval(
+                        round(count($rawMeasvalsOfThisSensor) / $maxVals['count'], 0)
+                    );
+        
+                    $takenValuesForNextSum = 0;
+                    $tmpMeasvalueSum = 0;
+                    $tmpTimestampSum = 0;
+        
+                    for ($i = 0; $i < count($rawMeasvalsOfThisSensor); $i++) {
+                        // loop through all measvals of the sensor
+                        $measvalue = $rawMeasvalsOfThisSensor[$i];
+                        
+                        if ($measvalue["sensorid"] === $sensor["id"]) {
+                            $tmpMeasvalueSum += $measvalue["measvalue"];
+                            $tmpTimestampSum += $measvalue["timestamp"];
+                            $takenValuesForNextSum += 1;
+                        }
+                        if ($takenValuesForNextSum === $countOfValuesForAvarage 
+                            || $i === count($rawMeasvalsOfThisSensor) - 1
+                        ) {
+                            array_push(
+                                $finalMeasvalsOfThisSensor,
+                                array(
+                                    "measvalue" => round(
+                                        $tmpMeasvalueSum / $takenValuesForNextSum, 2
+                                    ),
+                                    "timestamp" => round(
+                                        $tmpTimestampSum / $takenValuesForNextSum, 0
+                                    ),
+                                    "sensorid" => $sensor["id"]
+                                )
+                            );
+        
+                            $takenValuesForNextSum = 0;
+                            $tmpMeasvalueSum = 0;
+                            $tmpTimestampSum = 0;
+                        }
                     }
+                    break;
                 }
     
                 // insert the new vals of this sensor into the global new vals