diff --git a/CMakeLists.txt b/CMakeLists.txt
index eead043..8f21a88 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,6 +125,9 @@ target_link_libraries(motor-check openarm_can)
 add_executable(openarm-demo examples/demo.cpp)
 target_link_libraries(openarm-demo openarm_can)
 
+add_executable(openarm-diagnosis setup/openarm_can_diagnosis.cpp)
+target_link_libraries(openarm-diagnosis openarm_can)
+
 # Add tests
 if(BUILD_TESTING)
   # add_subdirectory(test)
diff --git a/setup/openarm_can_diagnosis.cpp b/setup/openarm_can_diagnosis.cpp
new file mode 100644
index 0000000..cbf436f
--- /dev/null
+++ b/setup/openarm_can_diagnosis.cpp
@@ -0,0 +1,181 @@
+// Copyright 2025 Enactic, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <linux/can.h>
+#include <linux/can/raw.h>
+#include <net/if.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <chrono>
+#include <cmath>
+#include <iostream>
+#include <openarm/can/socket/openarm.hpp>
+#include <openarm/damiao_motor/dm_motor_constants.hpp>
+#include <thread>
+#include <vector>
+
+// Return true if the netdev is configured for CAN-FD (MTU == CANFD_MTU), false if Classical (MTU ==
+// CAN_MTU)
+static bool iface_is_canfd(const char* ifname) {
+    int s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
+    if (s < 0) {
+        perror("socket");
+        return false;  // fall back
+    }
+    struct ifreq ifr{};
+    std::strncpy(ifr.ifr_name, ifname, IFNAMSIZ - 1);
+    ifr.ifr_name[IFNAMSIZ - 1] = '\0';
+    ifr.ifr_name[IFNAMSIZ] = '\0';
+    if (ioctl(s, SIOCGIFMTU, &ifr) < 0) {
+        perror("ioctl(SIOCGIFMTU)");
+        close(s);
+        return false;
+    }
+    close(s);
+    if (ifr.ifr_mtu == CANFD_MTU) return true;
+    if (ifr.ifr_mtu == CAN_MTU) return false;
+    std::cerr << "Warning: unexpected MTU " << ifr.ifr_mtu << " on " << ifname << "\n";
+    return false;
+}
+
+static const char* br_label(int br_code) {
+    // simple mapping example
+    switch (br_code) {
+        case 9:
+            return "5 Mbps";
+        case 4:
+            return "1 Mbps";
+        default:
+            return "(unknown)";
+    }
+}
+
+int main(int argc, char* argv[]) {
+    std::cout << "OpenArm CAN diagnostics\n";
+
+    // Args: <can_interface> [-fd]
+    if (argc < 2) {
+        std::cerr << "Usage: " << argv[0] << " <can_interface> [-fd]\n";
+        return 1;
+    }
+    std::string can_if = argv[1];
+    bool use_fd = false;
+    if (argc >= 3) {
+        std::string arg2 = argv[2];
+        if (arg2 == "-fd")
+            use_fd = true;
+        else {
+            std::cerr << "Error: Unknown argument '" << arg2 << "'. Use -fd to enable CAN-FD.\n";
+            return 1;
+        }
+    }
+
+    // Detect actual iface mode via MTU
+    bool iface_fd = iface_is_canfd(can_if.c_str());
+
+    std::cout << "CAN interface: " << can_if << std::endl;
+    std::cout << "Requested mode: " << (use_fd ? "CAN FD" : "Classical CAN") << std::endl;
+    std::cout << "Interface mode: " << (iface_fd ? "CAN FD" : "Classical CAN") << std::endl;
+
+    if (use_fd != iface_fd) {
+        std::cout << "WARNING: requested mode and interface mode differ. "
+                     "Check `ip link` configuration or run with/without -fd accordingly.\n";
+    }
+
+    std::cout << "Initializing OpenArm CAN..." << std::endl;
+    // Use the actual args
+    openarm::can::socket::OpenArm openarm(can_if, use_fd);
+
+    // Initialize arm motors
+    std::vector<openarm::damiao_motor::MotorType> motor_types = {
+        openarm::damiao_motor::MotorType::DM8009, openarm::damiao_motor::MotorType::DM8009,
+        openarm::damiao_motor::MotorType::DM4340, openarm::damiao_motor::MotorType::DM4340,
+        openarm::damiao_motor::MotorType::DM4310, openarm::damiao_motor::MotorType::DM4310,
+        openarm::damiao_motor::MotorType::DM4310};
+    std::vector<uint32_t> send_can_ids = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
+    std::vector<uint32_t> recv_can_ids = {0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17};
+    openarm.init_arm_motors(motor_types, send_can_ids, recv_can_ids);
+
+    // Initialize gripper
+    std::cout << "Initializing gripper..." << std::endl;
+    openarm.init_gripper_motor(openarm::damiao_motor::MotorType::DM4310, 0x08, 0x18);
+
+    openarm.set_callback_mode_all(openarm::damiao_motor::CallbackMode::PARAM);
+
+    std::cout << "Reading motor parameters ..." << std::endl;
+    openarm.query_param_all((int)openarm::damiao_motor::RID::MST_ID);
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    openarm.recv_all();
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    openarm.query_param_all((int)openarm::damiao_motor::RID::can_br);
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    openarm.recv_all();
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    // read params
+    const auto& arm_motors = openarm.get_arm().get_motors();
+    const auto& gripper_motors = openarm.get_gripper().get_motors();
+
+    std::vector<uint32_t> missing_ids;
+
+    for (size_t i = 0; i < arm_motors.size(); ++i) {
+        const auto& motor = arm_motors[i];
+        double mst = motor.get_param((int)openarm::damiao_motor::RID::MST_ID);
+        double br = motor.get_param((int)openarm::damiao_motor::RID::can_br);
+
+        if (mst < 0 || br < 0 || !std::isfinite(mst) || !std::isfinite(br)) {
+            std::cout << "[arm#" << i << "] id=0x" << std::hex << recv_can_ids[i] << std::dec
+                      << " -> NG (no response)\n";
+            missing_ids.push_back(recv_can_ids[i]);
+        } else {
+            std::cout << "[arm#" << i << "] queried_mst_id: " << static_cast<uint32_t>(mst)
+                      << "  queried_br: " << static_cast<int>(br) << " (" << br_label(static_cast<int>(br)) << ")\n";
+        }
+    }
+
+    for (size_t i = 0; i < gripper_motors.size(); ++i) {
+        const auto& gr = gripper_motors[i];
+        double mst = gr.get_param((int)openarm::damiao_motor::RID::MST_ID);
+        double br = gr.get_param((int)openarm::damiao_motor::RID::can_br);
+
+        if (mst < 0 || br < 0 || !std::isfinite(mst) || !std::isfinite(br)) {
+            std::cout << "[gripper] id=0x18 -> NG (no response)\n";
+            missing_ids.push_back(0x18);
+        } else {
+            std::cout << "[gripper] queried_mst_id: " << static_cast<uint32_t>(mst)
+                      << "  queried_br: " << static_cast<int>(br) << " (" << br_label(static_cast<int>(br)) << ")\n";
+        }
+    }
+
+    if (!missing_ids.empty()) {
+        std::cout << "NG: failed IDs:";
+        for (auto id : missing_ids) std::cout << " 0x" << std::hex << id;
+        std::cout << std::dec << std::endl;
+
+        std::cout << "Hints:\n";
+        std::cout << "  • Motor internal CAN bitrate may be different from host setting\n";
+        std::cout
+            << "  • USB2CAN adapter mode/config may be wrong (FD vs Classical, bitrate profile)\n";
+        std::cout << "  • Wiring/power/termination/ID conflict may exist\n";
+        return 2;
+    } else {
+        std::cout << "OK: all motors responded\n";
+        return 0;
+    }
+}