OvidiuNastac

Hi
As Steve wrote, the alarm is issued by the active encoder, which in your case, almost sure, is the scale. So you must verify the scale couples sealing (some times it could be the humidity from the environment) or the scale itself. From that I know, Gildemeister use pressured scales for their machines. So you must verify if the air pressure for the scale is OK and if it reaches at scale. Once I has had a similar issue and the problem was the humidity that covered the scale.
Olso could be a big lateral play in the slide ways.
I hope this will help you.
Nit

 Hi, Like "OvidiuNastac" said, you most possible using scale as you active encoder. I have had worked in the company with same DMG m/c, (Twin 65 and Twin 42)

how to make sure active encoder--going to services Axis--you can see you have active measuring system=2

that normally mean scale ( not 100%, I have now INDEX C200,  they using scale as 1st encoder and active, very stranger).

like  OvidiuNastac saying you need make sure your air system is clean and dry.

I fixed same alarms by add small air dryer and filter before air going into the scale air blowing system.

even every m/c shop air compressor have dryer but  in my former company comp. air still very damp. I can release water from filter dump hole every day some water.

but after the filter installed that error never happen again.

I have a problem with sinumerik, in HMI appears an alarm, 25000, Hardware fault of active encoder, it get active when I try to reference the axis, to be sure that both measurement systems are measuring, servo encoder and linear encoder, I see the screen where appears both measurement, I move by hand pushing and pulling the axis and te relation of both system are almost the same 4 microns of diference, but the problem appears at the moment of move the axis by control.

First time that alarm appear was when I take away the servo of its housing, and I think maybe is the cable, but I have the doubt because I can see the values of their position (servo and linear encoder) in the screen.

Can any body help us

[snip]

Best Regards

For sure it's not problem of HMI. 25000 indicate or hardware problem ( for example you can simulate cutting one phase wire of encoder cable) ar also from my experience electromagnetic noice or also vibration 

DM 36310 >=100 can exclude alarm, but dont solve the problem if you have hardware fault

Best Regards