PLCHandler Programming Guide - Esco Drives & Automation

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PLCHandler Programming Guide2 CPLCHandler Class2.1 Constructor and Configuration of the PLCHandlerA PLCHandler object of the CPLCHandler class always is assigned to a single PLC. Thus at creationof the object it has to be configured, with which PLC resp. which communication interface thePLCHandler should work. The configuration is specified in chapter 3.There are various constructors for creating the PLCHandler object:1. CPLCHandler(unsigned long ulId, char *pszIniFile,SysLog *pLogFile = NULL):Parameter ulId designates the index of the PLCHandler assumed that more instances areused.An ini-file for reading the configuration will be handed over to the constructor. The SDKprovides two sample files (OPCServerARTI.ini and OPCServerSimu.ini). The structure isdescribed in detail in the Appendix of this guide.Optionally a log file can be specified for recording all errors and internal states. The SysLogclass is contained in the PLCHandler.2. CPLCHandler(PlcConfig *pPlcConfig, PlcDeviceDesc *pDeviceDesc,SysLog *pLogFile = NULL):The parameters on the one hand define general configuration data in the PLCHandler(pPlcConfig) and on the other hand the communication settings for the (pDeviceDesc). Thedata are identic with the entries in the ini-file. Thus both constructors can be used according tothe actual requirements.Optionally also here a log file can be specified for recording all errors and internal states. TheSysLog class is contained in the PLCHandler.The PlcConfig structure contains the configuration data for the PLCHandler:struct PlcConfig{PlcConfig(void);~PlcConfig(void);unsigned long ulId;unique ID for every PLCchar *pszName; name of the PLCItfType it; interface type of the PLC (IT_ARTI, IT_GATEWAY, ...)char ulSize; size of the variablechar bActive; flag if the PLC is active or notchar bMotorola; flag if data has to be swapt for motorola byte orderchar bLogin; flag if the application can do a loginchar bLogToFile; flag if the application should log to a filechar bPreCheckIdentity; flag if the project identity will be checkedbefore every read / write of variablesunsigned long ulTimeout; communication timeout in msunsigned long ulNumTries; number of tries of receive's before throwing aCOMM_FATAL errorunsigned long ulWaitTime; total time in ms to wait for a reconnection to the PLCunsigned long ulReconnectTime; time interval in ms to try for a reconnectionchar *pszHwType; HW type of the PLC (PLCC_HW_STANDARD,PLCC_HW_MAX4)unsigned long ulHwVersion;unsigned long ulBufferSize;HW versioncommunication buffersize of the runtime systemrunning on the PLC; 0 = default sizechar *pszProjectName; name of the CoDeSys project running on theruntime system; only of interest in simulationchar *pszDllDirectory; directory where to find the (Sym-)ARTI Dll'sGatewayConnection *gwc; pointer to the gateway connection if using thegateway interface 3S - Smart Software Solutions GmbHPLCHandler Programmming Guide.doc Page 4 of 17
PLCHandler Programming Guideunsigned long ulLogFilter; Filter for log actions};The PlcDeviceDesc structure contains data to connect to a device:struct PlcDeviceDesc{PlcDeviceDesc(void);~PlcDeviceDesc(void);char* pszName; name of the device / protocolchar* pszInstance; instance name of the devicechar* pszProject; name of the project running on that device (only ofinterest for gateway)unsigned long ulNumParams; number of the device parametersPlcParameterDesc* ppd; pointer to an array of parameter descriptions};To get the definition of the PlcParameterDesc please have a look at the PLCHandler headerPlcConfig.h.3. CPLCHandler(SysLog *pLogFile = NULL):This constructor is used to create a PLCHandler object with default configuration (Interface:ARTI).But in each case before connection establishment the communication device must beconfigured (with SetConfig() or directly by opening the configuration with GetConfig() andsetting the appropriate values).2.2 Destructor (and connection termination)As soon as the PLCHandler object has been deleted, the connection to the PLC gets terminated (ifthere was one), all resources are deallocated and all internal threads are terminated.2.3 Connection establishmentMethod: long ::Connect(unsigned long ulTimeout = PLCHANDLER_USE_DEFAULT,unsigned long hStateChangedEvent = 0, int bLoadSymbols = 1)After the configuration has been done, via this method a connection to the PLC can be established.The method will return RESULT_OK (=0) as soon as the connection has been built up successfully. Incase of an error the current state of the communication resp. The last occurred error can be get by theGetStatus() resp. GetLastError().If a connection could not be established, the method returns an error and internally a thread will bestarted, trying to reconnect to the PLC in the defined reconnect interval.ulTimeout: This value specifies how long the connection establishment maximally can take,before the function returns. At 0 the value set actually in the configuration will be used (see:WaitTime). At ulTimeout = –1 the method will not return until a connection to the PLC will be set upsuccessfully. This can take any time.hStateChangedEvent: Here optionally the handle of an event can be passed which can be used toinform the client at each status change.bLoadSymbols: This parameter can be used to specify whether at a connection establishment thesymbols of the PLC should be loaded or not.Return value: If no error occurs, the function returns RESULT_OK. Otherwise, it returns …RESULT_FAILED: common error in the underlying interfaces. A specific error code can beretrieved by GetStatus() resp. GetLastError().RESULT_NO_CONFIGURATION: no configuration for this PLCHandler instance (Id unknown). 3S - Smart Software Solutions GmbHPLCHandler Programmming Guide.doc Page 5 of 17
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PLCHandler Programming Guide - Esco Drives & Automation

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