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DanioVision TCU - Feedback And Error Messages

Last updated: Jul 30, 2026

Feedback and Error Messages

The DanioVision Temperature Control Unit gives feedback about its status with four LED lights and error codes on the temperature display.

LED Indicators

Status LED Explanation User Action
Filling / Draining Orange – blinking System is pumping.
  • The system can be filled with water.
  • Water can be drained from the basin.
  • Cooling liquid can be filled.
Filling / Draining Red – continuous Time out. There has been no flow in the water circulation and/or the cooling liquid circulation for more than 10 minutes. Reset the system by turning the Operation switch to Off and then back to Fill/Drain.
Heating / Cooling Green – blinking The water is being heated/cooled to the set temperature. Wait. No action needed.
Ready Green – continuous The set temperature has been reached and the system is ready to be used. The Temperature Control Unit is ready to be used and an experiment can be started.
Error Red – 1 blink – repeatedly Insufficient flow in the water circulation.

Look for the source of the problem. This may be:

  • Low water level in the basin (due to evaporation or leakage). If so, fill the system.
  • Flow blockage somewhere in the system or filter clogged. Contact Noldus to replace the filter.
  • Pump failure.

The Fill/Drain mode can be used to localize the problem. Reset the system by setting the Operation switch to Off and then to Fill/Drain.
Error Red – 2 blinks – repeatedly Insufficient flow in the cooling liquid circulation.

Look for the source of the problem. This may be:

  • Low cooling liquid level in the pump reservoir. Check if the liquid level is above the indication. If not, refill cooling liquid and check for signs of leakage in the emergency liquid container.
  • Flow blockage somewhere in the system.
  • Pump failure.

The Fill/Drain mode can be used to localize the problem. Reset the system by setting the Operation switch to Off and then to Fill/Drain.
Error Red – 3 blinks – repeatedly The fan is not spinning, or not spinning at sufficient speed. Check if there is anything blocking the fan. If this is not the case, please contact Noldus support.
Error Red – 4 blinks – repeatedly System is overheated.

Turn off the system and end the experiment. Cooling liquid can be cooled down by switching the Operation switch to Fill/Drain. Search for the possible cause of the overheating:

  • Air vents of the Temperature Control Unit might be blocked so the radiator cannot get rid of its heat. Make sure air vents are free.
  • System is used in environmental conditions that have not been tested, for example, room temperature above 35°C.
Error Red – 5 blinks – repeatedly Heating and cooling have been activated simultaneously. An electrical problem has occurred. Please contact Noldus support.
Error Red – 6 blinks – repeatedly A problem with the data logger has occurred.
  1. Open the TCU and take the SD card out.
  2. If it is locked, unlock it.
  3. Check that it has a minimum capacity of 4 GB.
  4. Put the SD card back in the TCU.
  5. If the error persists, take the card out and format it (FAT32). Leave the card empty; do not copy the old files to the newly-formatted card.
  6. Put the SD card back in the TCU and restart the TCU.
Error Red – continuous A temperature deviation larger than 0.5°C above or below the set temperature has been detected. Water conditioning will continue to try to resolve the situation. Once resolved, the status of the system returns to 'Ready'. Depending on your protocol you can choose to continue or to abort the experiment.

Temperature Display

Status Codes

  • The water is being heated to the set temperature.
  • The water is being cooled to the set temperature.
  • The current water temperature is at least 0.5°C below the set temperature. Shown together with temperature alarm code E05. The red Error LED (continuous) is on.
  • The current water temperature is at least 0.5°C above the set temperature. Shown together with temperature alarm code E04. The red Error LED (continuous) is on.
  • Error mode indicator.
  • This is a system setting indicator, which blinks when the TCU is in heating/cooling mode. No action need be taken.
  • LCD is off: A possible reason is that one of the flat cables coming from the LCD display is not properly connected. Open the DV-TCU, locate the multi-color flat cable (3rd to the right of the SD card), disconnect it and connect it again.

Error Codes

Error Code Explanation User Action
E01 The temperature sensor is not detected. Please connect the temperature sensor cable (with cinch-plugs on both ends).
E04 'Too high' temperature alarm. The measured temperature is 0.5°C higher than the set temperature. Depending on your protocol you can choose to continue or abort the experiment. Note that this error also occurs while the system is heating/cooling before the start of the experiment; the system continues to heat/cool to try to resolve the error.
E05 'Too low' temperature alarm. The measured temperature is 0.5°C lower than the set temperature. Depending on your protocol you can choose to continue or abort the experiment. Note that this error also occurs while the system is heating/cooling before the start of the experiment.
Ed1 System error. See the Error status entry in the LED Indicators section above.

Source: DanioVision TCU Reference Manual, Noldus Information Technology

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