diff --git a/ADIS_ESP32_Eclipse/main/challenge_com.c b/ADIS_ESP32_Eclipse/main/challenge_com.c
index 6a30fd4..6b06fc1 100644
--- a/ADIS_ESP32_Eclipse/main/challenge_com.c
+++ b/ADIS_ESP32_Eclipse/main/challenge_com.c
@@ -26,14 +26,19 @@ const char MQTT_TOPIC_SF_CONFIG_SETUP[] = "/splitFlap/config/setup/";
 
 void Challenge_Com_ParseMqtt(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data){
 	/* INFO
-	 * TOPIC: 			event->topic
+	 * TOPIC: 			event->topic      ==> do not directly use, string is not limited
 	 * TOPIC LENGTH: 	event->topic_len
-	 * DATA: 			event->data
+	 * DATA: 			event->data       ==> do not directly use, string is not limited
 	 * DATA LENGTH: 	event->data_len
 	 * CLIENT: 			event->client
 	 */
 
     esp_mqtt_event_handle_t event = event_data;
+    // cut strings to length
+    char topic[event->topic_len+1]; char data[event->data_len+1];
+    McuUtility_strcpy((unsigned char*)topic, sizeof(topic), (unsigned char*)event->topic);
+    McuUtility_strcpy((unsigned char*)data, sizeof(data), (unsigned char*)event->data);
+
     bool handled = false;
 
     // check if event id is MQTT_EVENT_DATA => break if not
@@ -46,7 +51,7 @@ void Challenge_Com_ParseMqtt(void *handler_args, esp_event_base_t base, int32_t
     /* stationary robot allowed commands */
     if(Challenge_App_GetRobotMode() == true) {
     	// CMD: CONFIG SETUP
-        if(McuUtility_strcmp((char*)event->topic, MQTT_TOPIC_SF_CONFIG_SETUP)==0){
+        if(McuUtility_strcmp(topic, MQTT_TOPIC_SF_CONFIG_SETUP)==0){
         	handled = true;
         	// parse json
         	int setupId = 0;
@@ -56,35 +61,39 @@ void Challenge_Com_ParseMqtt(void *handler_args, esp_event_base_t base, int32_t
         	    {"hardwareId", t_integer, .addr.integer = &hwId,},
         	    {NULL},
         	};
-        	if(json_read_object(event->data, json_attrs, NULL) != 0){
-        		ESP_LOGE(TAG, "Parsing JSON data of CONFIG SETUP message failed. Event data was = %s", event->data);
+        	int err = json_read_object(data, json_attrs, NULL);
+        	if(err != 0){
+        		ESP_LOGE(TAG, "Parsing JSON data of CONFIG SETUP message failed. Event data was = %s", data);
+        		ESP_LOGE(TAG, "Parse error was: %s", json_error_string(err));
         	} else{  // successfully parsed
         		// check values
-        		if(setupId >= 0 && setupId <= 10 && hwId >= 0 && hwId <= 10){
+        		if(setupId >= 0 && setupId <= 10 && hwId >= 0 && hwId <= 50){
     				SplitFlap_Wrapper_SetHardwareIdentifier(setupId, hwId);
         		} else{
-        			ESP_LOGE(TAG, "SetupID or HardwareID out of range. Event data was = %s", event->data);
+        			ESP_LOGE(TAG, "SetupID or HardwareID out of range. Event data was = %s", data);
         		}
         	}
         }
         // CMD: INIT ALL
-        else if(McuUtility_strcmp((char*)event->topic, MQTT_TOPIC_SF_INITALL)==0){
+        else if(McuUtility_strcmp(topic, MQTT_TOPIC_SF_INITALL)==0){
         	handled = true;
         	SplitFlap_Wrapper_MoveAllToZeroPosition();
         }
         // CMD: DISPLAY
-        else if(McuUtility_strcmp((char*)event->topic, MQTT_TOPIC_SF_DISPLAY)==0){
+        else if(McuUtility_strcmp(topic, MQTT_TOPIC_SF_DISPLAY)==0){
         	handled = true;
         	// parse json
-        	unsigned char message[] = "TST";
+        	char message[10] = "TEST";
         	struct json_attr_t json_attrs[] = {
-				{"message", t_string, .addr.string = (char*)message},
+				{"message", t_string, .addr.string = message, .len = sizeof(message)},
 				{NULL},
 			};
-        	if(json_read_object(event->data, json_attrs, NULL) != 0){
-				ESP_LOGE(TAG, "Parsing JSON data of DISPLAY message failed. Event data was = %s", event->data);
+        	int err = json_read_object(data, json_attrs, NULL);
+        	if(err != 0){
+				ESP_LOGE(TAG, "Parsing JSON data of DISPLAY message failed. Event data was = %s", data);
+				ESP_LOGE(TAG, "Parse error was: %s", json_error_string(err));
 			} else{  // successfully parsed
-	        	SplitFlap_Wrapper_Display(message);
+	        	SplitFlap_Wrapper_Display((unsigned char*)message);
 			}
         }
     }
@@ -98,7 +107,7 @@ void Challenge_Com_ParseMqtt(void *handler_args, esp_event_base_t base, int32_t
 
 
     if(handled == false){
-        ESP_LOGE(TAG, "Received data could not be handled. Topic was %s", event->topic);
+        ESP_LOGE(TAG, "Received data could not be handled. Topic was %s", topic);
     }
     return;
 }