diff --git a/include/openarm/can/socket/openarm.hpp b/include/openarm/can/socket/openarm.hpp
index 5f7b8e5..666e259 100644
--- a/include/openarm/can/socket/openarm.hpp
+++ b/include/openarm/can/socket/openarm.hpp
@@ -28,6 +28,9 @@ public:
     OpenArm(const std::string& can_interface, bool enable_fd = false);
     ~OpenArm() = default;
 
+    std::string can_interface() const noexcept { return can_interface_; }
+    bool can_fd_enabled() const noexcept { return enable_fd_; }
+
     // Component initialization
     void init_arm_motors(const std::vector<damiao_motor::MotorType>& motor_types,
                          const std::vector<uint32_t>& send_can_ids,
diff --git a/src/openarm/damiao_motor/dm_motor_device_collection.cpp b/src/openarm/damiao_motor/dm_motor_device_collection.cpp
index 3ec8e05..eca9027 100644
--- a/src/openarm/damiao_motor/dm_motor_device_collection.cpp
+++ b/src/openarm/damiao_motor/dm_motor_device_collection.cpp
@@ -55,7 +55,7 @@ void DMDeviceCollection::set_zero_all() {
 }
 
 void DMDeviceCollection::refresh_one(int i) {
-    auto dm_device = get_dm_devices()[i];
+    auto dm_device = get_dm_devices().at(i);
     auto& motor = dm_device->get_motor();
     CANPacket refresh_packet = CanPacketEncoder::create_refresh_command(motor);
     send_command_to_device(dm_device, refresh_packet);