Door open close single step problem

Guys,

got one Okuma Lb 25 lathe here doing strange things.
Although the sensors for "door opened" and "door closed" work perfectly ( they give right response in the OSP data when moving the door)...
one cannot run the single step mode for testing
programs with opened door like at any other Okuma lathe we run. I just can run single step with fully closed door OR...

Strange but true, if I manually manipulate the door opened sensor. Then
single step testing is possible ALTHOUGH the door is stil open and the OSP knows it is: both door closed AND door opened sensors give positives feedback simultaneously....WTF!?!

Is it a software error? Any parameter maybe set wrong?

Hi,
the issue you describe is usually caused by a wrong parameter state in the safety chain (door interlock logic).
On some Okuma LB-series machines the OSP can show both “door open” and “door closed” signals if one of the intermediate safety relays is sticky or gives delayed feedback.

A few things worth checking:

Safety relay for the door circuit (often in the OSP-input rack) – they sometimes fail mechanically and give dual-state feedback.

Parameter for single-step mode (Operation/Interlock settings) – if it was changed in the past, single step won’t start unless the OSP sees a strict closed-door state.

Check the I/O monitor while operating the door – see if any input bit flickers or stays “on” for too long.

Door proximity sensors sometimes give perfect live values but still fail under load or vibration.

If you want, I can check the parameter list or the logic for your machine type (LB25, OSP-xxx).
We repair and diagnose Okuma controls, drives and boards daily, so the issue is quite familiar.

You can contact us here:
https://cnc-elektronik.de/en/

(We work with machines across Europe.)

Let me know what OSP version and machine year you have — then I can point you to the exact parameters.

Der Beitrag wurde von Vetael bearbeitet: 22.11.2025, 03:54 Uhr