diff --git a/src/src/main/java/com/my/graphiteDigesterBg/diframe/connection/DiConSerialPort.java b/src/src/main/java/com/my/graphiteDigesterBg/diframe/connection/DiConSerialPort.java
index c0558e9..ed7a963 100644
--- a/src/src/main/java/com/my/graphiteDigesterBg/diframe/connection/DiConSerialPort.java
+++ b/src/src/main/java/com/my/graphiteDigesterBg/diframe/connection/DiConSerialPort.java
@@ -116,7 +116,9 @@ public class DiConSerialPort implements DiDeviceConnection {
         } else if ( 0x02 == messageType ) { // error message
             throw new RuntimeException("error message received: " + DiByteBuffer.toHex(this.receivedData));
         } else {
-            throw new RuntimeException("unknown message type : " + messageType + " <= " + DiByteBuffer.toHex(this.receivedData));
+            var hex = DiByteBuffer.toHex(this.receivedData);
+            this.receivedData = null;
+            throw new RuntimeException("unknown message type : " + messageType + " <= " + hex);
         }
     }