diff --git a/mbus/mbus-protocol-aux.c b/mbus/mbus-protocol-aux.c
index 6f96d87..ead7cd0 100755
--- a/mbus/mbus-protocol-aux.c
+++ b/mbus/mbus-protocol-aux.c
@@ -1811,6 +1811,57 @@ mbus_send_request_frame(mbus_handle * handle, int address)
     return retval;
 }
 
+//------------------------------------------------------------------------------
+// send a user data packet from master to slave
+//------------------------------------------------------------------------------
+int
+mbus_send_user_data_frame(mbus_handle * handle, int address, const unsigned char *data, size_t data_size)
+{
+    int retval = 0;
+    mbus_frame *frame;
+
+    if (mbus_is_primary_address(address) == 0)
+    {
+        MBUS_ERROR("%s: invalid address %d\n", __PRETTY_FUNCTION__, address);
+        return -1;
+    }
+
+    if (data == NULL)
+    {
+        MBUS_ERROR("%s: Invalid data\n", __PRETTY_FUNCTION__);
+        return -1;
+    }
+
+    if ((data_size > MBUS_FRAME_DATA_LENGTH) || (data_size == 0))
+    {
+        MBUS_ERROR("%s: illegal data_size %d\n", __PRETTY_FUNCTION__, data_size);
+        return -1;
+    }
+
+    frame = mbus_frame_new(MBUS_FRAME_TYPE_LONG);
+
+    if (frame == NULL)
+    {
+        MBUS_ERROR("%s: failed to allocate mbus frame.\n", __PRETTY_FUNCTION__);
+        return -1;
+    }
+
+    frame->control = MBUS_CONTROL_MASK_SND_UD | MBUS_CONTROL_MASK_DIR_M2S;
+    frame->address = address;
+    frame->control_information = MBUS_CONTROL_INFO_DATA_SEND;
+    frame->data_size = data_size;
+    memcpy(frame->data, data, data_size);
+
+    if (mbus_send_frame(handle, frame) == -1)
+    {
+        MBUS_ERROR("%s: failed to send mbus frame.\n", __PRETTY_FUNCTION__);
+        retval = -1;
+    }
+
+    mbus_frame_free(frame);
+    return retval;
+}
+
 //------------------------------------------------------------------------------
 // send a request from master to slave and collect the reply (replies)
 // from the slave.
diff --git a/mbus/mbus-protocol-aux.h b/mbus/mbus-protocol-aux.h
index c2a255a..08093a6 100755
--- a/mbus/mbus-protocol-aux.h
+++ b/mbus/mbus-protocol-aux.h
@@ -287,6 +287,18 @@ int mbus_send_switch_baudrate_frame(mbus_handle * handle, int address, long baud
  */
 int mbus_send_request_frame(mbus_handle * handle, int address);
 
+/**
+ * Sends user data frame (SND_UD) to given slave using "unified" handle
+ *
+ * @param handle    Initialized handle
+ * @param address   Address (0-255)
+ * @param data      User data
+ * @param data_size Byte count of user data
+ *
+ * @return Zero when successful.
+ */
+int mbus_send_user_data_frame(mbus_handle * handle, int address, const unsigned char *data, size_t data_size);
+
 /**
  * Sends a request and read replies until no more records available
  * or limit is reached.