motor stops when runing at 9000 RPM

Hello

I'm using a synchronous spindle with sinumerik 840Di sl,sinamics 120 and CU 320. This spindle has an incremental encoder 1 Vpp sin/cos.

The problem is that when the spindle is running about 9000 RPM suddenly stops with this alarm:

(231125:amplitude error track A/B)

Someone knows how to solve the problem?? ( I checked something about the EMC but I'm not sure...)

Check the value in r0949 & report here.

Also check the encoder cable & its shield connection.

I've cheked and I see that the encoder A signal falls down at this speed below 0,8 V (tolerance is 0,8-1,1V). Now I'm changing the encoder and I will see and post the result.

update: the encoder was broken