diff --git a/bin/mbus-serial-request-data.c b/bin/mbus-serial-request-data.c
index 46526a7..b6a9834 100755
--- a/bin/mbus-serial-request-data.c
+++ b/bin/mbus-serial-request-data.c
@@ -132,7 +132,7 @@ main(int argc, char **argv)
         }
     }   
 
-    if (mbus_recv_frame(handle, &reply) != 0)
+    if (mbus_recv_frame(handle, &reply) != MBUS_RECV_RESULT_OK)
     {
         fprintf(stderr, "Failed to receive M-Bus response frame.\n");
         return 1;
diff --git a/bin/mbus-serial-scan.c b/bin/mbus-serial-scan.c
index 1d2d0f8..a2c14c9 100755
--- a/bin/mbus-serial-scan.c
+++ b/bin/mbus-serial-scan.c
@@ -103,7 +103,7 @@ main(int argc, char **argv)
         
         ret = mbus_recv_frame(handle, &reply);
 
-        if (ret == -3)
+        if (ret == MBUS_RECV_RESULT_TIMEOUT)
         {
             continue;
         }
@@ -111,7 +111,7 @@ main(int argc, char **argv)
         if (debug)
             printf("\n");
         
-        if (ret == -2)
+        if (ret == MBUS_RECV_RESULT_INVALID)
         {
             /* check for more data (collision) */
             mbus_purge_frames(handle);
diff --git a/bin/mbus-serial-select-secondary.c b/bin/mbus-serial-select-secondary.c
index 624a384..66b4d4b 100755
--- a/bin/mbus-serial-select-secondary.c
+++ b/bin/mbus-serial-select-secondary.c
@@ -79,13 +79,13 @@ main(int argc, char **argv)
 
     ret = mbus_recv_frame(handle, &reply);
 
-    if (ret == -3)
+    if (ret == MBUS_RECV_RESULT_TIMEOUT)
     {
         printf("No reply from device with secondary address %s: %s\n", argv[2], mbus_error_str());
         return 1;
     }    
 
-    if (ret == -2)
+    if (ret == MBUS_RECV_RESULT_INVALID)
     {
         printf("Invalid reply from %s: The address address probably match more than one device: %s\n", argv[2], mbus_error_str());
         return 1;
@@ -99,7 +99,7 @@ main(int argc, char **argv)
             return 1;
         }
 
-        if (mbus_recv_frame(handle, &reply) != 0)
+        if (mbus_recv_frame(handle, &reply) != MBUS_RECV_RESULT_OK)
         {
             printf("Failed to recieve reply from selected secondary device: %s\n", mbus_error_str());
             return 1;
diff --git a/bin/mbus-serial-switch-baudrate.c b/bin/mbus-serial-switch-baudrate.c
index e67b98c..49cc969 100755
--- a/bin/mbus-serial-switch-baudrate.c
+++ b/bin/mbus-serial-switch-baudrate.c
@@ -78,7 +78,7 @@ main(int argc, char **argv)
 
     ret = mbus_recv_frame(handle, &reply);  
     
-    if (ret == -3)
+    if (ret == MBUS_RECV_RESULT_TIMEOUT)
     {
         printf("No reply from device\n");
         return 1;
diff --git a/bin/mbus-tcp-request-data.c b/bin/mbus-tcp-request-data.c
index 1ed504f..2e23c5d 100755
--- a/bin/mbus-tcp-request-data.c
+++ b/bin/mbus-tcp-request-data.c
@@ -117,7 +117,7 @@ main(int argc, char **argv)
         }
     }   
 
-    if (mbus_recv_frame(handle, &reply) != 0)
+    if (mbus_recv_frame(handle, &reply) != MBUS_RECV_RESULT_OK)
     {
         fprintf(stderr, "Failed to receive M-Bus response frame: %s\n", mbus_error_str());
         return 1;
diff --git a/bin/mbus-tcp-scan.c b/bin/mbus-tcp-scan.c
index 2776018..10d4165 100755
--- a/bin/mbus-tcp-scan.c
+++ b/bin/mbus-tcp-scan.c
@@ -86,7 +86,7 @@ main(int argc, char **argv)
         
         ret = mbus_recv_frame(handle, &reply);
 
-        if (ret == -3)
+        if (ret == MBUS_RECV_RESULT_TIMEOUT)
         {
             continue;
         }
@@ -94,7 +94,7 @@ main(int argc, char **argv)
         if (debug)
             printf("\n");
         
-        if (ret == -2)
+        if (ret == MBUS_RECV_RESULT_INVALID)
         {
             /* check for more data (collision) */
             mbus_purge_frames(handle);
diff --git a/bin/mbus-tcp-select-secondary.c b/bin/mbus-tcp-select-secondary.c
index 5268650..5795d83 100755
--- a/bin/mbus-tcp-select-secondary.c
+++ b/bin/mbus-tcp-select-secondary.c
@@ -65,13 +65,13 @@ main(int argc, char **argv)
 
     ret = mbus_recv_frame(handle, &reply);
 
-    if (ret == -3)
+    if (ret == MBUS_RECV_RESULT_TIMEOUT)
     {
         printf("No reply from device with secondary address %s: %s\n", argv[3], mbus_error_str());
         return 1;
     }    
 
-    if (ret == -2)
+    if (ret == MBUS_RECV_RESULT_INVALID)
     {
         printf("Invalid reply from %s: The address address probably match more than one device: %s\n", argv[3], mbus_error_str());
         return 1;
@@ -85,7 +85,7 @@ main(int argc, char **argv)
             return 1;
         }
 
-        if (mbus_recv_frame(handle, &reply) != 0)
+        if (mbus_recv_frame(handle, &reply) != MBUS_RECV_RESULT_OK)
         {
             printf("Failed to recieve reply from selected secondary device: %s\n", mbus_error_str());
             return 1;
diff --git a/mbus/mbus-protocol-aux.c b/mbus/mbus-protocol-aux.c
index cb11257..f7f9dc9 100755
--- a/mbus/mbus-protocol-aux.c
+++ b/mbus/mbus-protocol-aux.c
@@ -1434,13 +1434,13 @@ mbus_recv_frame(mbus_handle * handle, mbus_frame *frame)
     if (handle == NULL)
     {
         MBUS_ERROR("%s: Invalid M-Bus handle for receive.\n", __PRETTY_FUNCTION__);
-        return -1;
+        return MBUS_RECV_RESULT_ERROR;
     }
 
     if (frame == NULL)
     {
         MBUS_ERROR("%s: Invalid frame.\n", __PRETTY_FUNCTION__);
-        return -1;
+        return MBUS_RECV_RESULT_ERROR;
     }
 
     result = handle->recv(handle, frame);
@@ -1463,7 +1463,8 @@ int mbus_purge_frames(mbus_handle *handle)
     while (1)
     {
         err = mbus_recv_frame(handle, &reply);
-        if (err != -2 && err != 0)
+        if (err != MBUS_RECV_RESULT_OK && 
+            err != MBUS_RECV_RESULT_INVALID)
             break;
 
         received = 1;
@@ -1660,7 +1661,7 @@ mbus_sendrecv_request(mbus_handle *handle, int address, mbus_frame *reply, int m
         if (debug)
             printf("%s: debug: receiving response frame #%d\n", __PRETTY_FUNCTION__, frame_count);
     
-        if (mbus_recv_frame(handle, next_frame) != 0)
+        if (mbus_recv_frame(handle, next_frame) != MBUS_RECV_RESULT_OK)
         {
             MBUS_ERROR("%s: Failed to receive M-Bus response frame.\n", __PRETTY_FUNCTION__);
             retval = 1;
@@ -1802,12 +1803,12 @@ mbus_select_secondary_address(mbus_handle * handle, const char *mask)
 
     ret = mbus_recv_frame(handle, &reply);
 
-    if (ret == -3)
+    if (ret == MBUS_RECV_RESULT_TIMEOUT)
     {
         return MBUS_PROBE_NOTHING;
     }    
 
-    if (ret == -2)
+    if (ret == MBUS_RECV_RESULT_INVALID)
     {
         /* check for more data (collision) */
         mbus_purge_frames(handle);
@@ -1862,12 +1863,12 @@ mbus_probe_secondary_address(mbus_handle * handle, const char *mask, char *match
 
         ret = mbus_recv_frame(handle, &reply);
 
-        if (ret == -3)
+        if (ret == MBUS_RECV_RESULT_TIMEOUT)
         {
             return MBUS_PROBE_NOTHING;
         }
 
-        if (ret == -2)
+        if (ret == MBUS_RECV_RESULT_INVALID)
         {
             return MBUS_PROBE_COLLISION;
         }
diff --git a/mbus/mbus-protocol.h b/mbus/mbus-protocol.h
index 5fa5298..6742100 100755
--- a/mbus/mbus-protocol.h
+++ b/mbus/mbus-protocol.h
@@ -106,6 +106,15 @@ typedef struct _mbus_slave_data {
 #define MBUS_HANDLE_TYPE_TCP    0
 #define MBUS_HANDLE_TYPE_SERIAL 1
 
+//
+// Resultcodes for mbus_recv_frame
+//
+#define MBUS_RECV_RESULT_OK        0
+#define MBUS_RECV_RESULT_ERROR     -1
+#define MBUS_RECV_RESULT_INVALID   -2
+#define MBUS_RECV_RESULT_TIMEOUT   -3
+#define MBUS_RECV_RESULT_RESET     -4
+
 //------------------------------------------------------------------------------
 // MBUS FRAME DATA FORMATS
 //
diff --git a/mbus/mbus-serial.c b/mbus/mbus-serial.c
index d28e7eb..5880e27 100755
--- a/mbus/mbus-serial.c
+++ b/mbus/mbus-serial.c
@@ -245,7 +245,7 @@ mbus_serial_recv_frame(mbus_handle *handle, mbus_frame *frame)
     if (handle == NULL || frame == NULL)
     {
         fprintf(stderr, "%s: Invalid parameter.\n", __PRETTY_FUNCTION__);
-        return -1;
+        return MBUS_RECV_RESULT_ERROR;
     }
 
     memset((void *)buff, 0, sizeof(buff));
@@ -264,7 +264,7 @@ mbus_serial_recv_frame(mbus_handle *handle, mbus_frame *frame)
         {
        //     fprintf(stderr, "%s: aborting recv frame (remaining = %d, len = %d, nread = %d)\n",
          //          __PRETTY_FUNCTION__, remaining, len, nread);
-            return -1;
+            return MBUS_RECV_RESULT_ERROR;
         }
 
 //   printf("%s: Got %d byte [remaining %d, len %d]\n", __PRETTY_FUNCTION__, nread, remaining, len);
@@ -288,7 +288,7 @@ mbus_serial_recv_frame(mbus_handle *handle, mbus_frame *frame)
     if (len == 0)
     {
         // No data received
-        return -1;
+        return MBUS_RECV_RESULT_TIMEOUT;
     }
     
     //
@@ -301,16 +301,16 @@ mbus_serial_recv_frame(mbus_handle *handle, mbus_frame *frame)
     {
         // Would be OK when e.g. scanning the bus, otherwise it is a failure.
         // printf("%s: M-Bus layer failed to receive complete data.\n", __PRETTY_FUNCTION__);
-        return -2;
+        return MBUS_RECV_RESULT_INVALID;
     }
 
     if (len == -1)
     {
         fprintf(stderr, "%s: M-Bus layer failed to parse data.\n", __PRETTY_FUNCTION__);
-        return -1;
+        return MBUS_RECV_RESULT_ERROR;
     }
   
-    return 0;
+    return MBUS_RECV_RESULT_OK;
 }
 
 
diff --git a/mbus/mbus-tcp.c b/mbus/mbus-tcp.c
index f81a1cd..5dde42b 100755
--- a/mbus/mbus-tcp.c
+++ b/mbus/mbus-tcp.c
@@ -169,7 +169,7 @@ int mbus_tcp_recv_frame(mbus_handle *handle, mbus_frame *frame)
 
     if (handle == NULL || frame == NULL) {
         fprintf(stderr, "%s: Invalid parameter.\n", __PRETTY_FUNCTION__);
-        return -1;
+        return MBUS_RECV_RESULT_ERROR;
     }
 
     memset((void *) buff, 0, sizeof(buff));
@@ -190,14 +190,14 @@ retry:
 
             if (errno == EAGAIN || errno == EWOULDBLOCK) {
                 mbus_error_str_set("M-Bus tcp transport layer response timeout has been reached.");
-                return -3;
+                return MBUS_RECV_RESULT_TIMEOUT;
             }
 
             mbus_error_str_set("M-Bus tcp transport layer failed to read data.");
-            return -1;
+            return MBUS_RECV_RESULT_ERROR;
         case 0:
             mbus_error_str_set("M-Bus tcp transport layer connection closed by remote host.");
-            return -4;
+            return MBUS_RECV_RESULT_RESET;
         default:
             len += nread;
         }
@@ -211,10 +211,10 @@ retry:
 
     if (remaining < 0) {
         mbus_error_str_set("M-Bus layer failed to parse data.");
-        return -2;
+        return MBUS_RECV_RESULT_INVALID;
     }
 
-    return 0;
+    return MBUS_RECV_RESULT_OK;
 }