To use the full potential of POWERLINK the stack allows you to interact at several stages of the protocol. For example, you may receive a callback after the device transition to a new communication state.

goal_eplNewStateInd - Indicate transition to a new communcation state

This function will be indicated at the slave, if it will be forced to another communication state. It is called before the transition change. This user interface ensures a save behavior of the application, before the node goes to another state. Additionally, a change to READY_TO_OPERATE can be prevent.

Returns a GOAL_STATUS_T as result.

See nmtslave.c for a demonstration.

goal_eplSwResetInd - Reset the device

This function will reset the device. It's called after a "NMT SwReset" command was received.

In this function the devices should be reinitialized completely. All application parameters from the Object Dictionary are set to the default values before this function is called. The user has to ensure that his application will be reset. Additionally, it is possible for the application to load parameters from a nonvolatile memory. Returns a GOAL_STATUS_T as result.

See nmtslave for a demonstration.

goal_eplResetApplInd - Reset the application

This function will reset the device's application. It's called after a "NMT Reset Node" command was received.

All application parameters from the Object Dictionary are set to the default values before this function is called. The user has to ensure that his application will be reset. Additionally, it is possible for the application to load parameters from a nonvolatile memory. Returns a GOAL_STATUS_T as result.

goal_eplResetCommInd - Reset communication parameters

This function is user defined. It is called after a "NMT Reset Communication" command was received.

All communication parameters from the Object Dictionary besides the node ID are set to the default values before this function is called. The default values are taken from the object dictionary's "default" value, stored as defaultVal in the object dictionary's VALUE_DESC_T struct. In this function the EPL node can get a new node id from a DIP-Switch or nonvolatile memory. Further communication parameters can be loaded from a nonvolatile memory too. In this case the object dictionary values have to be overwritten using goal_eplPutObj() and goal_eplSetCommPar() . Returns a GOAL_STATUS_T as result.

See nmtslave for a demonstration.

goal_eplResetConfInd - Reset configuration

This function is user defined. It is called after a "NMT Reset Configuration" command was received.

In this function the EPL node can get a new node id from a DIP-Switch or nonvolatile memory. Further communication parameters can be loaded from a nonvolatile memory too. In this case the object dictionary values have to be overwritten using goal_eplPutObj() and goal_eplSetCommPar() . Returns a GOAL_STATUS_T as result.

See nmtslave for a demonstration.

goal_eplGetEplNodeId - Get the node ID of the device

This function has to be filled by the user. It returns the node ID, in the range of 1..254, of the device from e.g. a DIP switch or nonvolatile memory to the EPL layer.

It is called from the EPL layer to initialize the node. Returns a GOAL_STATUS_T as result.

goal_eplSdoInitCon - Init SDO connection finished

This function is called after a SDO connection was established or the initialization was aborted. It has to be filled by the user. The parameter flgTimeout gets the information for a timeout or success. Returns a GOAL_STATUS_T as result.

goal_eplSdoWrInd - Indicate the occurence of a SDO write access

This function is called if an SDO write request reaches the EPL SDO server. Parameters of the function are the Index and Sub Index of the entry in the local object dictionary where the data should be written to.

If numerical data with size up to 4 bytes should be written, the library stores the previous value in temporary buffer. The new value is put into the local object dictionary.

If the application does not accept this new value, i.e. the function returns with a value > 0, the old value is restored from the temporary buffer to the object dictionary and the SDO write request will be answered with an abort domain transfer by the library. The abort code can be specified by the return -value.

The return value, which has to be specified by the application, selects the possible protocol answer of the write request to the SDO server.

Returns a GOAL_STATUS_T as result. Typical values are listed in the following table.

goal_eplSdoRdInd - Indicate the occurence of a SDO read access

This function determines a reaction to the device for an index - subindex read access via SDO. With this function the object dictionary has to be made up to date e.g. by reading of digital inputs. If an error occurs an abort domain transfer will be started.

The return value, which has to be specified by the application, selects the possible protocol answer of the write request to the SDO server.

Returns a GOAL_STATUS_T as result. Typical values are listed in the following table.

goal_eplTestSdoValue - Check the value of a SDO before writing to object dictionary

This function is called before a write access to an object should be done. At this point the EPL library has been tested the correctness of the attributes for this object. The user can start further tests for this write access. If the return value is not GOAL_OK the write access will be refused.

Parameter are index, subindex, pointer to the data (little endian format) and the length of the data. The function is called immediately after receiving the first message - in the case of a segmented transfer not all data may be available. Returns a GOAL_STATUS_T as result.

goal_eplSdoWrCon - Confirmation function for SDO write access

This function signs that the message sent by goal_eplWriteSdoReq() was confirmed by the SDO server. It handles errors and is useful for program synchronization. If the flgError isn't zero, the last SDO transfer was terminated by an abort domain transfer. Returns a GOAL_STATUS_T as result.

The reason for the termination contains the flgError.

goal_eplSdoRdCon - Confirmation function for SDO read access

This functions signs that the message sent by goal_eplReadSdoReq() was confirmed by the SDO Server. It handles errors and is useful for program synchronization. If the flgError isn't zero, the last SDO transfer was terminated by an abort domain transfer. The flgError contains the reason for the termination. In case of success the parameter pObj from goal_eplReadSdoReq() points to the read value. Returns a GOAL_STATUS_T as result.

goal_eplSdoClosedInd - Connection closed indication

This function indicates, that a SDO connection is closed by the remote node. Returns a GOAL_STATUS_T as result.

goal_eplNewPdoValueInd - User indication for new rxPdo values

The function is called by the plc driver when a new value of mapped object of a rxPdo is received. Returns a GOAL_STATUS_T as result.

goal_eplDllErrorInd - Indicate errors on the Data Link Layer

This function has to be filled by the user. It indicates a physical error on the ethernet bus on the propagation of the EPL frames and errors on the EPL Data Link Layer. The Errors are handled by the Library and the drivers itself. So, this indication is only an information for the user. On communication error the user should reset the application. Returns a GOAL_STATUS_T as result.

The following errors are indicated by the DLL error code (as far as they are supported from the ethernet controller):

goal_eplPdoErrorInd - PDO error indication

This function indicates, that a PDO error occurred. Based on the PDO number the user is able to appraise the error in detail. Returns a GOAL_STATUS_T as result.

goal_eplLedInd - Set POWERLINK leds

This function indicates, that the POWERLINK status or error indication led has to be changed. Returns a GOAL_STATUS_T as result.

goal_soaInd - Update the transmit PDO data

This function updates the the data objects of the transmit PDO before the POWERLINK stack assembles the PDO object. No returns.