My NCU 710.2 (6FC5371-0AA10-0AA2) just got replaced in my lathe which has a 840D SL controller.

Upon start up the sequence stops and the seven segment LED display flashes d2.

Does anyone know what this means and how we can repair it?

Brett

Dear sir;

After replacing the NCU unit, you  have to reload the machine archives from the HMI to that replaced unit. Do you make this step?

Hi yes we know that. We can’t get the NCU to boot up past the d2 fault on the 7 segment display.

Do you know what d2 fault means?

Yes, CF card checked, tried another card with same result. Same fault with or without CF card inserted. All status LEDs are orange as per initial boot sequence. Seven segment display flashing "d" - "2." - "d" - "2." continuously. Any idea what this means? Siemens must know because they programmed it. Where is this fault documented?