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Force a firmware download to MLC (in case of no response).
Tags: PLC Download

Force Download Mode for MLCs:

In case the PLC is not responding for the firmware download command and when it does not allow the further

download in the unit, PLC can be driven in the Force download mode. Follow the following step to enter the force

download mode.



  1. Power off the unit
  2. Remove all communication cables. No need to remove USB cable.
  3. Short the pin 2 and 8 of Com1 (RJ45). (Prepare a cable for this by cutting one end off so you can twist together the bare leads for 2 and 8).
  4. Turn the Run/Halt switch to halt position.
  5. Power on the unit.
  6. Wait for 10 Seconds.
  7. Unit enters the Force download mode. The indication is that the Run and Error LEDs start blinking at 1 sec interval.
  8. Download the firmware first, using USB or Com1 RS232 cable.
  9. The device remains in the “Force Download Mode” only for one minute. After one minute it exits from this mode and executes the firmware if it is valid. This is indicated by turning off Run and Error LEDs.
Content Created by Derek Thompson