tie(_gpsNode, "mode", SGRawValueMethods<GPS, const char*>(*this, &GPS::getMode, NULL));
tie(_gpsNode, "command", SGRawValueMethods<GPS, const char*>(*this, &GPS::getCommand, &GPS::setCommand));
tie(_gpsNode, "mode", SGRawValueMethods<GPS, const char*>(*this, &GPS::getMode, NULL));
tie(_gpsNode, "command", SGRawValueMethods<GPS, const char*>(*this, &GPS::getCommand, &GPS::setCommand));