Update the date field to the date & time of the node being updated

I am sure that I am missing something very simple here, so I hope somebody can put me on the right track.

Use Case:

  1. I have a simple content type “Article”
  2. A date field of type: “Date and Time” is attached to this content type.
  3. Using any of “Rules” or “Business rules” module, I need when updating a node of type “Article”, to set the value of the “date field” to be equal to the “date and time” of the node being updated.

What is the right token that must be used ?

So far:

I have been trying for days with no success, I have tried to use the below token but yet no sucess:

  • [node:changed:custom:D-M-Y-H:i:s]
  • [node:changed:custom:D-M-Y H:i:s]
  • [node:changed:custom:D/M/Y H:i:s]
  • [node:changed:custom:DMYHis]

Any help PLEASE!!

Thank you,