Wrote some simple code to use the DataAccessService to read and write from the GDS. It doesn’t work. with $ cat /opt/plcnext/projects/runtime/logs/runtime.log, I find the following line: RscServiceManager DEBUG - Unknown service requested: Arp.Plc.Gds.Services.IDataAccessService #include "DataAccess.hpp" #include "Arp/System/Rsc/ServiceManager.hpp" using namespace Arp::System::Rsc; void DataAccess::init() { Log::Info("Calling DataAccess::init"); DataAccessServicePtr = ServiceManager::GetService(); if(DataAccessServicePtr != NULL){ Log::Info("DataAccess class initialised"); } } bool DataAccess::read() { Log::Info("Calling DataAccess::read"); bool bool_in = false; ReadItem readPortData = this->DataAccessServicePtr->ReadSingle("Arp.Plc.Eclr/ModbusTCP.test_port_in"); if(readPortData.Error == DataAccessError::None){ readPortData.Value.CopyTo(bool_in); Log::Info("read from test port: ", bool_in); } else{ Log::Info("Error reading from GDS."); } return bool_in; } #include #include "Arp/Plc/Gds/Services/IDataAccessService.hpp" #include "Arp/System/Commons/Logging.h" using namespace std; using namespace Arp; using namespace Arp::Plc::Gds::Services; using namespace Arp::System::Commons::Diagnostics::Logging; #ifndef DATA_ACCESS_H_ #define DATA_ACCESS_H_ class DataAccess { private: bool initialised; IDataAccessService::Ptr DataAccessServicePtr; bool bool_in; public: void init(); bool read(); }; #endif // DATA_ACCESS_H_ What have I done wrong?