Reading Device Info - Developer Docs

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. 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:

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

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
Python

#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);

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

./build/hand2/2_hand_info

Measured Output

On a right-hand Wuji Hand 2 with all 20 joints online:

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.

Subscribing With Callbacks: how nid behaves in joint_states
Publishing Control Commands: how array index and nid are used in control APIs
Troubleshooting: fault codes and how to handle them

​Overview

​Prerequisites

​Hardware

​Software

​Two Joint Numbering Schemes

​Data Flow

​Runtime Handling

​Integration Steps

​Running It

​Measured Output

​Adapting It

​Testing Whether a Joint Is Online

​Reference Ranges for Temperature and Voltage

​Investigating Fault Codes

​Locating a Specific Joint

​Related

Overview

Prerequisites

Hardware

Software

Two Joint Numbering Schemes

Data Flow

Runtime Handling

Integration Steps

Running It

Measured Output

Adapting It

Testing Whether a Joint Is Online

Reference Ranges for Temperature and Voltage

Investigating Fault Codes

Locating a Specific Joint

Related