diff --git a/aqhome/serial.c b/aqhome/serial.c
index 1281459..ac3599f 100644
--- a/aqhome/serial.c
+++ b/aqhome/serial.c
@@ -15,6 +15,7 @@
 
 #include <gwenhywfar/misc.h>
 #include <gwenhywfar/debug.h>
+#include <gwenhywfar/text.h>
 
 #include <string.h>
 
@@ -116,6 +117,9 @@ int AQH_Serial_Open(AQH_SERIAL *sr)
   }
 
   sr->fd=fd;
+
+  _attnHigh(sr);
+
   return 0;
 }
 
@@ -380,6 +384,7 @@ int _check(const uint8_t *ptr, uint8_t len)
   }
   if (x) {
     DBG_ERROR(NULL, "Bad checksum");
+    GWEN_Text_DumpString(ptr, len, 2);
     return GWEN_ERROR_GENERIC;
   }
 
@@ -438,7 +443,14 @@ int _readFromFd(AQH_SERIAL *sr)
     }
     else {
       if (sr->bytesToRead==0) {
-        /* msg received, handle */
+        /* msg received, check */
+        if (_check(sr->readBuffer, sr->readPos)<0) {
+          DBG_INFO(0, "here (%d)", rv);
+          sr->readPos=0;
+          sr->bytesToRead=2;
+          return 0;
+        }
+        /* valid msg received, handle */
         AQH_Serial_PacketReceived(sr, sr->readBuffer, sr->readPos);
         sr->readPos=0;
         sr->bytesToRead=2;
@@ -502,7 +514,7 @@ int AQH_Serial_StartWriting(AQH_SERIAL *sr, const uint8_t *ptr, uint8_t len)
     return rv;
   }
 
-  usleep(10);
+  usleep(50);
   return 0;
 }
 
@@ -516,7 +528,7 @@ int AQH_Serial_Loop(AQH_SERIAL *sr)
   struct timeval tv;
   int rv;
 
-  tv.tv_sec=5;
+  tv.tv_sec=2;
   tv.tv_usec=0;
 
   if (sr->bytesToWrite) {
@@ -528,6 +540,10 @@ int AQH_Serial_Loop(AQH_SERIAL *sr)
 
   rv=select(sr->fd+1, &readSet, (sr->bytesToWrite)?(&writeSet):NULL, NULL, &tv);
   if (rv<0) {
+    if (errno!=EINTR) {
+      DBG_ERROR(NULL, "Error on select");
+      return GWEN_ERROR_IO;
+    }
   }
   else if (rv) {
     if (FD_ISSET(sr->fd, &readSet)) {
@@ -545,6 +561,11 @@ int AQH_Serial_Loop(AQH_SERIAL *sr)
       }
     }
   }
+  else if (rv==0) {
+    /* timeout */
+    sr->readPos=0;
+    sr->bytesToRead=2;
+  }
 
   return 0;
 }