ifstream ifs(slave_file.c_str());
if (ifs.is_open() == false) {
log_error("%s: %s failed to read data from file: %s\n", id.c_str(), get_device_type().c_str(), slave_file.c_str());
ifstream ifs(slave_file.c_str());
if (ifs.is_open() == false) {
log_error("%s: %s failed to read data from file: %s\n", id.c_str(), get_device_type().c_str(), slave_file.c_str());