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4. Troubleshooting

Symptom Likely cause Jump to
KAREL variables show unexpected values Variables never initialized KAREL variables are uninitialized
Robot moves to the wrong pose or overwrites another program's register Exchange or detection registers collide with existing usage Register conflicts
Socket errors, no response from the device Network / socket messaging misconfigured Communication errors
High reprojection error, inaccurate detections Too few or too similar calibration poses Insufficient calibration accuracy
Object detected but robot stops at the wrong height uniVision height offset or tool frame incorrect Height offset in detected poses
Negative value in an exchange register Vision device returned an error code Error codes returned by the device
Calibration hangs, no prompt shown Program inactive or Deadman switch not held No user prompts during calibration

KAREL variables are uninitialized

  • Run the KAREL program W_LIBRARY once to set the default values. It will return a cam error on the first run, but that is expected. After that, adjust the variables to your use case under Data → Karel Vars. See Installation & Setup → Initialize the KAREL variables.
  • Make sure the system variable $KAREL_ENB is set to 1 (Menu → Next → System → Variables). Without it, KAREL files cannot be used.

Register conflicts

  • The KAREL library writes its results to exchange registers (R[60]–R[62], PR[60], SR[60] by default) and uses PR[65] for the detection pose and R[63] for the PTP/LIN switch. Check that these do not conflict with the registers used by your own programs and change them via the KAREL variables if required. See Robot Program → Exchange registers.
  • If you change the detection pose register, update both the TP programs and the w_detect_pose_reg KAREL variable.

Communication errors

  • Verify that the network configuration matches your setup: robot controller IP (e.g. 192.168.100.11) under Menu → (6) Setup → Setup 2 → (9) Host Comm. → TCP/IP, and the Machine Vision Device (default 192.168.100.1, port 32006) under the Host Comm Clients.
  • Make sure the client tag configured in Host Comm (e.g. C1:) matches the w_client_tag KAREL variable.
  • Ensure the robot server on the vision device is active: device website → Jobs → Processing Instance → Robot Server, with Generic selected as the robot manufacturer.
  • Check general network connectivity and firewall rules between the controller and the device.

Insufficient calibration accuracy

  • Use more than five calibration poses (seven to eleven give better results). Add them to the W_CALIB_POSES array (Data → Karel Pos).
  • Increase the variation between poses — especially in the pose angles. The variance of the calibration movements matters more than the variance of the poses.
  • Make sure the calibration target covers as much of the camera image as possible and is fully visible.
  • Prefer a wenglor ZVZJ calibration target over a printed one.
  • Check the reprojection error returned by calc_calibration — high values indicate a poor calibration.

For the general calibration guidelines, see the Wenglor Robot Server overview in the wenglor robot vision manual.

Height offset in detected poses

  • Check that the uniVision job is set properly, especially the height offset from the calibration target to the object in Device Robot Vision.
  • Ensure the correct tool frame (TCP) is active. See Installation & Setup → Tool setup.

Error codes returned by the device

If the robot server returns a negative error code (-5001 … -5010), the KAREL library passes it through unchanged into the exchange register (or string register) that the calling routine writes to. This indicates a problem on the vision-device side, not in the KAREL library itself. For the meaning of each code, see Generic Robot Vision Interface → Error codes in the wenglor robot vision manual.

No user prompts during calibration

  • The calibration process uses user prompts shown under Menu → User. Make sure the program is active so it can read the input.
  • To answer a prompt, press Deadman switch + SHIFT + F1 (YES) or Deadman switch + SHIFT + F2 (NO) at the same time.