Synchronization of V90: randomly slave has fault F31100

Hello dear,

i did synchronization of V90 drives but randomly slave has fault F31100 , i checked all of things , i program this drive on positioning and working with any problem ???? What happen i use 1511

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Split from How to do position synchronize 2 axis on vertical movement ?.

The manual says: 

I have no idea why this happens. You should create a Support Request.

Hello dear,

i have the same problem 

here i bought near 14 servo drives of siemens products and big plc 1515T , I have serious problem that makes me confused. I start these servo motors on positioning mode without any problem but when i use two tested servo motors in synchronized mode one of them randomly has F31100 and encoder fault. Please explain me what happen when i use two servo as a master and slave.