> ## Documentation Index > Fetch the complete documentation index at: https://docs.wuji.tech/llms.txt > Use this file to discover all available pages before exploring further. # Reading Device Info ## Overview After connecting, print the device's static information and current diagnostic state in one pass: handedness, IP, online-joint bitmap, labels and effort limits for all 20 joints, plus each joint's status word, current, bus voltage, temperature, and error code. This is the first step in diagnosing a device. Offline joints, abnormal temperatures, and non-zero fault codes are all visible at a glance. Matching example: `examples/c/wuji_hand_2/2_hand_info.c`. For the complete list of device parameters and operations, see [Device Parameters and Operations](/en/docs/wuji-hand/latest/sdk-reference/device-operations). This page covers only how to run it and what the measurements show. Python has no standalone example, though every capability is available: `hand.handedness()`, `hand.ip()`, `hand.online_joints_count()`, `hand.joints`, `hand.effort_limit()`, and a `joint_diagnostics` subscription for the diagnostic snapshot. This example only reads. It doesn't enable the motors, and the fingers don't move. ## Prerequisites ### Hardware | Item | Requirement | | - | - | | Wuji Hand 2 | 1 | | Connection | Ethernet | ### Software | Item | Requirement | | - | - | | Operating system | Ubuntu 22.04 LTS or later | | Wuji SDK | v2026.8.31 or later | | C toolchain | CMake 3.16 or later, plus the extracted SDK package | ## Two Joint Numbering Schemes This is the key to reading both this example's output and `joint_states`. | Numbering | Values | Used by | | - | - | - | | **Array index** | Contiguous 0 through 19 | Subscripts for array APIs such as `effort_limit`, `mit_params`, and `joint_command` | | **`nid`** | 1–4, 6–9, 11–14, 16–19, 21–24 | Firmware bus node IDs, appearing in `joint_states` and `joint_diagnostics` | Each finger occupies a block of 5 nids but uses only the first 4, so 5, 10, 15, and 20 are skipped. The conversion holds across all 20 joints: ```text theme={null} nid = (index // 4) * 5 + (index % 4) + 1 ``` | Index | Label | nid | | - | - | - | | 0 | `thumb_S1` | 1 | | 3 | `thumb_S4` | 4 | | 4 | `index_S1` | 6 | | 7 | `index_S4` | 9 | | 8 | `middle_S1` | 11 | | 19 | `pinky_S4` | 24 | **Using an `nid` from `joint_states` directly as an array subscript shifts everything.** ## Data Flow ```mermaid theme={null} flowchart TD CONN["wuji_connect()"] STATIC["static information
handedness / ip / online_joints_count"] BITMAP["online bitmap
one bit per joint index"] PERJ["per-joint information
label / online state / effort limit"] DIAG["joint_diagnostics snapshot
status word / current / voltage / temperature / error code"] CONN --> STATIC STATIC --> BITMAP BITMAP --> PERJ PERJ --> DIAG ``` The online bitmap is a 32-bit integer where bit N corresponds to the joint at index N. With all 20 joints online it reads `0x000FFFFF`. ## Runtime Handling | Branch point | Behavior | What to do | | - | - | - | | Joint offline | Its bitmap bit is 0 and the joint is marked `offline` | Check bus wiring and power | | Non-zero error code | The `err_code` column isn't `0x0000` | Look up the fault code and call `clear_fault()` if needed | | Elevated temperature | The `temp` column reads high | At rest, measurements ranged from 49 to 59 degrees Celsius | | Several devices | The example connects to the first it finds | On a shared network, name a serial number | ## Integration Steps ```c theme={null} #include "wuji_sdk.h" /* 1. Static information */ WujiHandedness side; wuji_hand_2_handedness(dev, &side); char ip[64]; wuji_dev_ip(dev, ip, sizeof(ip)); uint32_t online = 0; wuji_hand_2_online_joints_count(dev, &online); /* 2. Online bitmap and per-joint information */ uint32_t bitmap = 0; wuji_hand_2_online_joints_bitmap(dev, &bitmap); for (int i = 0; i < 20; i++) { const char *label = wuji_hand_2_joint_label(i); bool is_online = (bitmap >> i) & 1; float lim = 0; wuji_hand_2_get_effort_limit(dev, i, &lim); } /* 3. Diagnostic snapshot: one subscribed frame is enough */ struct WujiSub *sub = NULL; wuji_hand_2_subscribe_joint_diagnostics(dev, on_diag, &ctx, &sub); /* Read nid / status_word / current / vbus / temperature / error_code in the callback */ wuji_sub_close(sub); ``` ```python theme={null} from wuji_sdk import DeviceType, SdkManager manager = SdkManager.instance() hands = [d for d in manager.scan() if d.device_type == DeviceType.WujiHand2] hand = manager.connect(sn=hands[0].sn, device_name="hand") # 1. Static information print("handedness:", hand.handedness().get()) print("ip:", hand.ip().get()) print("online joints:", hand.online_joints_count().get()) # 2. Per-joint effort limits, indexed 0..19 print("effort_limit:", hand.effort_limit().get()) # 3. Diagnostic snapshot: take one frame from a subscription sub = hand.joint_diagnostics().subscribe() frame = sub.recv() for e in frame.joints: print(e.nid, hex(e.status_word.raw) if hasattr(e.status_word, "raw") else e.status_word) sub.close() manager.disconnect_all() ``` ## Running It ```bash theme={null} ./build/hand2/2_hand_info ``` ### Measured Output On a right-hand Wuji Hand 2 with all 20 joints online: ```text theme={null} Connecting to WH2KA00XXXXXXXXX (192.168.1.100:7447) handedness: right ip: 192.168.1.100 online joints (count): 20 online bitmap = 0x000FFFFF (20 joints online) i label state effort_lim 0 thumb_S1 online 1.500A 1 thumb_S2 online 1.500A 2 thumb_S3 online 1.500A 3 thumb_S4 online 1.500A 4 index_S1 online 1.500A ... 19 pinky_S4 online 1.500A joint_diagnostics snapshot (20 joints): nid status_word current vbus temp err_code 1 0x24620001 0.00A 12.3V 54.8C 0x0000 2 0x24620001 -0.01A 12.4V 55.4C 0x0000 ... 24 0x24620001 0.01A 12.3V 55.8C 0x0000 ``` | Metric | Measured | | - | - | | Online bitmap | `0x000FFFFF`, all 20 bits set | | Joint labels | `thumb_S1` through `pinky_S4`, 4 per finger | | Effort limit | 1.500 A across the board | | Status word | `0x24620001` across the board | | Bus voltage | 12.3 to 12.4 V | | Temperature | 49.1 to 58.6 degrees Celsius | | Error code | `0x0000` across the board | | Current at rest | −0.02 to +0.01 A | At rest and unenabled, current fluctuates slightly around zero and temperature holds near 50 degrees Celsius. That's a normal state. ## Adapting It ### Testing Whether a Joint Is Online The bitmap beats querying one at a time. `(bitmap >> i) & 1` equal to 1 means the joint at index i is online. Note that this uses the **array index**, not the nid. ### Reference Ranges for Temperature and Voltage At rest, temperature measured 49 to 59 degrees Celsius and bus voltage 12.3 to 12.4 V. Temperature rises after sustained large motions, and a persistently high reading calls for checking cooling and load. ### Investigating Fault Codes When `err_code` is non-zero, look it up in the fault code table. Clear faults with `clear_fault()`, and a fault that won't clear means the condition is still present. ### Locating a Specific Joint To go from a label to an nid, use the formula above. To go from an nid back to a label, compute `i = (nid - 1) // 5 * 4 + (nid - 1) % 5`, noting that nids 5, 10, 15, and 20 correspond to no joint. ## Related * [Subscribing With Callbacks](/en/docs/wuji-hand/latest/sdk-practice/subscribe-callback): how nid behaves in `joint_states` * [Publishing Control Commands](/en/docs/wuji-hand/latest/sdk-practice/publish-command): how array index and nid are used in control APIs * [Troubleshooting](/en/docs/wuji-sdk/troubleshooting/): fault codes and how to handle them This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.