when the sinumerik boots up the keys on the controller unit panel starts flashing

Nifash

(0)

Dear Sir or Madam

Hi hope you'refine.
I'm having issue with my siemens controller unit 840d.the model and type of the machine which i'm working with is Durma cnc machine(RP9).my problem is that when the sinumerik boots up the keys on the controller unit panel starts flashing and it goes on for like hours and i have to leave it on for hours until it stops flashing.i assume that the connection between the plc and the panel might be wrong but i'm not sure.it's been like that for days.I would be really grateful if you could help me to eliminate this annoying issue.

your kindness and prompt attention will be highly appreciated.

Yours faithfully

Nima