diff -r f859d567f94e -r 42b62867574d include/ecrt.h
--- a/include/ecrt.h	Fri Jan 22 10:11:58 2016 +0100
+++ b/include/ecrt.h	Fri Jan 22 13:09:43 2016 +0100
@@ -815,7 +815,7 @@
         uint16_t slave_position, /**< Slave position. */
         uint16_t index, /**< Index of the SDO. */
         uint8_t subindex, /**< Subindex of the SDO. */
-        uint8_t *data, /**< Data buffer to download. */
+        const uint8_t *data, /**< Data buffer to download. */
         size_t data_size, /**< Size of the data buffer. */
         uint32_t *abort_code /**< Abort code of the SDO download. */
         );
@@ -834,7 +834,7 @@
         ec_master_t *master, /**< EtherCAT master. */
         uint16_t slave_position, /**< Slave position. */
         uint16_t index, /**< Index of the SDO. */
-        uint8_t *data, /**< Data buffer to download. */
+        const uint8_t *data, /**< Data buffer to download. */
         size_t data_size, /**< Size of the data buffer. */
         uint32_t *abort_code /**< Abort code of the SDO download. */
         );
@@ -956,8 +956,10 @@
  *
  * Has to be called cyclically by the application after ecrt_master_activate()
  * has returned.
- */
-void ecrt_master_send(
+ *
+ * Returns the number of bytes sent.
+ */
+size_t ecrt_master_send(
         ec_master_t *master /**< EtherCAT master. */
         );
 
@@ -1145,6 +1147,17 @@
                                      */
         );
 
+/** Configure whether a slave allows overlapping PDOs.
+ *
+ * Overlapping PDOs allows inputs to use the same space as outputs on the frame.
+ * This reduces the frame length.
+ */
+void ecrt_slave_config_overlapping_pdos(
+        ec_slave_config_t *sc, /**< Slave configuration. */
+        uint8_t allow_overlapping_pdos /**< Allow overlapping PDOs */
+        );
+
+
 /** Add a PDO to a sync manager's PDO assignment.
  *
  * This method has to be called in non-realtime context before