Added ecrt_master_read_idn() and ecrt_master_write_idn() to read/write SoE

IDNs ad-hoc using the library.

include/ecrt.h

@@ -75,7 +75,9 @@
  * - Removed 'const' from argument of ecrt_sdo_request_state(), because the
  *   userspace library has to modify object internals.
  * - Added 64-bit data access macros.
- * - Added ecrt_slave_config_idn() method for storing SoE IDN configurations.
+ * - Added ecrt_slave_config_idn() method for storing SoE IDN configurations,
+ *   and ecrt_master_read_idn() and ecrt_master_write_idn() to read/write IDNs
+ *   ad-hoc via the user-space library.
  *
  * @{
  */
@@ -661,6 +663,44 @@ int ecrt_master_sdo_upload(
         uint32_t *abort_code /**< Abort code of the SDO upload. */
         );
 
+/** Executes an SoE write request.
+ *
+ * Starts writing an IDN and blocks until the request was processed, or an
+ * error occurred.
+ *
+ * \retval  0 Success.
+ * \retval -1 An error occured.
+ */
+int ecrt_master_write_idn(
+        ec_master_t *master, /**< EtherCAT master. */
+        uint16_t slave_position, /**< Slave position. */
+        uint16_t idn, /**< SoE IDN (see ecrt_slave_config_idn()). */
+        uint8_t *data, /**< Pointer to data to write. */
+        size_t data_size, /**< Size of data to write. */
+        uint32_t *error_code /**< Pointer to variable, where an SoE error code
+                               can be stored. */
+        );
+
+/** Executes an SoE read request.
+ *
+ * Starts reading an IDN and blocks until the request was processed, or an
+ * error occurred.
+ *
+ * \retval  0 Success.
+ * \retval -1 An error occured.
+ */
+int ecrt_master_read_idn(
+        ec_master_t *master, /**< EtherCAT master. */
+        uint16_t slave_position, /**< Slave position. */
+        uint16_t idn, /**< SoE IDN (see ecrt_slave_config_idn()). */
+        uint8_t *target, /**< Pointer to memory where the read data can be
+                           stored. */
+        size_t target_size, /**< Size of the memory \a target points to. */
+        size_t *result_size, /**< Actual size of the received data. */
+        uint32_t *error_code /**< Pointer to variable, where an SoE error code
+                               can be stored. */
+        );
+
 #endif /* #ifndef __KERNEL__ */
 
 /** Finishes the configuration phase and prepares for cyclic operation.