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MN50-LCD changes the displayed value to zero when connected to a 100 series controller.


The 50 series version of the LCD unit can fail to re-poll analogue values when used in conjunction with an old series MN controller, this will only occur after the controller has been power cycled. This problem does not apply to the 50 series controller range.


MicroNet 50 series LCD connected to 100 series controller.


With older controllers, although the initial poll from the LCD brings back the controller analogue values, the LCD changes the displayed value to zero. This issue does not affect digital state displays, or the analogue values contained within the controller’s scheme.


A temporary work around is to ensure the controller is not power cycled after its configuration has been downloaded.
Firmware version MNLCD5W is now available for correcting this issue.
If you require updated firmware for your MN50-LCD or MN50-LCDP units. Please contact the Product Support Services department.
Specification numbers affected:

  • MN50-LCD  (Firmware version MNLCD5V)
  • MN50-LCDP  (Firmware version MNLCD5V)

This issue will only affect the MN50-LCD or MN50-LCDP when used with the

  • MNN-30-100
  • MNN-44-100
  • MNN-50-100
  • MNN-62-100
  • Liberty (All variants)

This problem does not apply to the 50 series controller range.

Firmware version MNLCD5W is available from Product Support
By supplying the site name, and the number of MN50-LCD firmware EEPROMs required. 

Procedure to change the MN50-LCD firmware.

  1. Observe standard electrostatic precautions.
  2. Power the MN50-LCD/P and MicroNet 100 series controller down.
  3. If MN50-LCD remove the LCD from the controller and unplug the ribbon cable.
  4. If MN50-LCDP remove the power/communications plug from the LCDP, then remove the back cover.
  5. Remove the MN50-LCD/p's firmware EEPROM from IC13 socket. (Highlighted in the below image in blue)
  6. Carefully line up the legs of the new EEPROM with the socket.
  7. Press the new MNLCD5W firmware EEPROM into the socket.
  8. Restore the power to the controller
  9. Download the controller and LCD program to the controller.
  10. Restore the power and plug the MN50-LCD/P into the controller and allow it to upload is configuration.
  11. Check all analogue readings are now reading satisfactorily.

Updated January 2014.
The MicroNet 50 series range MN350,450,550,650 LCD and Touchscreen have been withdrawn from sale.
Currently no direct replacement is offered.
A limited number of MNLCD5W firmware EEPROMs are available.

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Revision #:
2 of 2
Last update:
‎2018-09-11 03:57 AM
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