diff --git a/bin/mbus-serial-request-data-multi-reply.c b/bin/mbus-serial-request-data-multi-reply.c
index d0a1abe..edfe091 100755
--- a/bin/mbus-serial-request-data-multi-reply.c
+++ b/bin/mbus-serial-request-data-multi-reply.c
@@ -104,10 +104,10 @@ main(int argc, char **argv)
     }
     
     frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
-    frame->address = MBUS_ADDRESS_BROADCAST_NOREPLY;
+    frame->address = MBUS_ADDRESS_NETWORK_LAYER;
     
     if (debug)
-        printf("%s: debug: sending init frame\n", __PRETTY_FUNCTION__);
+        printf("%s: debug: sending init frame #1\n", __PRETTY_FUNCTION__);
     
     if (mbus_send_frame(handle, frame) == -1)
     {
@@ -116,8 +116,27 @@ main(int argc, char **argv)
         return 1;
     }
     
-    mbus_recv_frame(handle, &reply);
+    while (mbus_recv_frame(handle, &reply) != -1);
     
+    //
+    // resend SND_NKE, maybe the first get lost
+    //
+    
+    frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
+    frame->address = MBUS_ADDRESS_NETWORK_LAYER;
+
+    if (debug)
+        printf("%s: debug: sending init frame #2\n", __PRETTY_FUNCTION__);
+
+    if (mbus_send_frame(handle, frame) == -1)
+    {
+        fprintf(stderr, "Failed to send mbus frame.\n");
+        mbus_frame_free(frame);
+        return 1;
+    }
+
+    while (mbus_recv_frame(handle, &reply) != -1);
+
     if (strlen(addr_str) == 16)
     {
         // secondary addressing
@@ -153,7 +172,7 @@ main(int argc, char **argv)
     
     // instead of the send and recv, use this sendrecv function that 
     // takes care of the possibility of multi-telegram replies (limit = 16 frames)
-    if (mbus_sendrecv_request(handle, address, &reply, 16) == -1)
+    if (mbus_sendrecv_request(handle, address, &reply, 16) != 0)
     {
         fprintf(stderr, "Failed to send/receive M-Bus request.\n");
         return 1;
diff --git a/bin/mbus-serial-scan-secondary.c b/bin/mbus-serial-scan-secondary.c
index 7de7c87..b395c63 100755
--- a/bin/mbus-serial-scan-secondary.c
+++ b/bin/mbus-serial-scan-secondary.c
@@ -133,7 +133,7 @@ main(int argc, char **argv)
     // init slaves
     //
     frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
-    frame->address = 0xFD;
+    frame->address = MBUS_ADDRESS_NETWORK_LAYER;
 
     if (mbus_send_frame(handle, frame) == -1)
     {
@@ -145,7 +145,7 @@ main(int argc, char **argv)
     (void) mbus_recv_frame(handle, &reply);
 
     frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
-    frame->address = 0xFF;
+    frame->address = MBUS_ADDRESS_BROADCAST_NOREPLY;
 
     if (mbus_send_frame(handle, frame) == -1)
     {
diff --git a/bin/mbus-tcp-request-data-multi-reply.c b/bin/mbus-tcp-request-data-multi-reply.c
index bdd5790..1a8ff58 100755
--- a/bin/mbus-tcp-request-data-multi-reply.c
+++ b/bin/mbus-tcp-request-data-multi-reply.c
@@ -136,7 +136,7 @@ main(int argc, char **argv)
     
     // instead of the send and recv, use this sendrecv function that 
     // takes care of the possibility of multi-telegram replies (limit = 16 frames)
-    if (mbus_sendrecv_request(handle, address, &reply, 16) == -1)
+    if (mbus_sendrecv_request(handle, address, &reply, 16) != 0)
     {
         fprintf(stderr, "Failed to send/receive M-Bus request.\n");
         return 1;
diff --git a/bin/mbus-tcp-scan-secondary.c b/bin/mbus-tcp-scan-secondary.c
index 5b31472..ab77f67 100755
--- a/bin/mbus-tcp-scan-secondary.c
+++ b/bin/mbus-tcp-scan-secondary.c
@@ -81,7 +81,7 @@ main(int argc, char **argv)
     // init slaves
     //
     frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
-    frame->address = 0xFD;
+    frame->address = MBUS_ADDRESS_NETWORK_LAYER;
 
     if (mbus_send_frame(handle, frame) == -1)
     {
@@ -94,7 +94,7 @@ main(int argc, char **argv)
     sleep(1);
 
     frame->control = MBUS_CONTROL_MASK_SND_NKE | MBUS_CONTROL_MASK_DIR_M2S;
-    frame->address = 0xFF;
+    frame->address = MBUS_ADDRESS_BROADCAST_NOREPLY;
 
     if (mbus_send_frame(handle, frame) == -1)
     {
diff --git a/mbus/mbus-protocol-aux.c b/mbus/mbus-protocol-aux.c
index e402c66..6132728 100755
--- a/mbus/mbus-protocol-aux.c
+++ b/mbus/mbus-protocol-aux.c
@@ -1437,8 +1437,14 @@ mbus_recv_frame(mbus_handle * handle, mbus_frame *frame)
         return -1;
     }
 
+    if (frame == NULL)
+    {
+        MBUS_ERROR("%s: Invalid frame.\n", __PRETTY_FUNCTION__);
+        return -1;
+    }
+
     result = handle->recv(handle, frame);
-    
+
     if (frame != NULL)
     {
         /* set timestamp to receive time */
@@ -1645,6 +1651,8 @@ mbus_sendrecv_request(mbus_handle *handle, int address, mbus_frame *reply, int m
     //
     next_frame = reply;
     
+    memset((void *)&reply_data, 0, sizeof(mbus_frame_data));
+    
     while (more_frames)
     {
         frame_count++;