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embedded_systems:ethercat:ethercatinterface:understanding_ethercatinterface [2019-04-16 10:53] – mgehrig2embedded_systems:ethercat:ethercatinterface:understanding_ethercatinterface [2019-06-24 16:35] – graf
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-====== Understanding EtherCatInterface ====== +====== ecmasterlib  ====== 
-===== ecmasterlib =====+===== Summary ===== 
 The //"ecmasterlib"// provides a callback function (''void callbackFct(...)'') which is called by the Acontis stack once per EtherCAT cycle. The //"ecmasterlib"// provides a callback function (''void callbackFct(...)'') which is called by the Acontis stack once per EtherCAT cycle.
 This method: This method:
Zeile 11: Zeile 12:
  
 When an //"ecmasterlib"// object is created, an instance (monotonic) is created. When an //"ecmasterlib"// object is created, an instance (monotonic) is created.
-The stack is started exactly as in the //"EcMasterDemoDC"// of Acontis. +The stack is started in the same way as in the //"EcMasterDemoDC"// of Acontis.
- +
- +
-===== EtherCatInterfaceBase ===== +
-This is the base class for all interface classes. +
-It mainly provides ''set'' and ''get'' methods for 8, 16, and 32 bit long data. +
-The get methods calculate the correct offset of the receive buffer of the //"ecmasterlib"// and returns the data. +
-The set methods also calculate the offset and write the data into the transmit buffer of //"ecmasterlib"//. +
- +
-==== EtherCatInterfaceBase_config.hpp ==== +
- +
- +
-===== EtherCatInterfaceElmo ===== +
-The //"EtherCatInterfaceElmo"// is especially designed for the Gold Twitter drives from Elmo. +
-It consists of the following components: +
-  * EtherCatInterfaceElmo.hpp +
-  * EtherCatInterfaceElmo.cpp +
-  * EtherCatInterfaceElmo_config.hpp +
- +
-The //"EtherCatInterfaceElmo.hpp"// declares all methods of the interface. +
-The low level methods ('ll_'-prefix) are at the bottom of the page. +
- +
-These low level methods read and write individual data objects to/from the stack. +
-Which objects are available and their file type must be read from the documentation of the manufacturer of the EtherCAT slave. +
-Each data object has its own method. +
- +
-Where a data object is located in the PDO depends on the ENI file used. +
-These offsets must be read from the ENI file and configured in //"EtherCatInterfaceElmo_config.hpp"//. +
- +
-All methods above the low level methods are optional. +
-They contain a certain degree of intelligence and simplify the interface to the user application. +
- +
-==== Blocking functions ==== +
-Methods in the interface must never be **blocking**. +
- +
-Some advanced functions may take several cycles. +
-They are only completed when they return ''true''. +
-These methods must be called again in each cycle until they return ''true''. +
- +
-==== EtherCatInterfaceElmo_config.hpp ==== +
-This is configuration file has do be adapted depending on the EtherCAT network. +
- +
-The most important part of this file is the offset definition of all PDO offset. +
-Before you start your application, you have to define all PDO offsets of your network.+
  
-Be aware that EtherCATInterface assumes that all drives send the identical variables via PDO. 
-With the current implementation it is not possible to send different variables for different drives. 
  
-If a variable is not available, the offset is set to '-1'. 
-The methods which would use a unavailable variable will throw an error if called. 
  

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