I have three sinamics s120 drives on a machine.. one of the drives is the master and the other two are speed ratios to the master.. I have the encoder unsmoothed tag from the master feeding the two slaves. Then, I use the setpoint adder to send the drive the ratio I need.. It appears that the speed reference going to the drives bounces around quite a bit.. I see 3-8 RPM Variation.. I did all the rotational tuning on the drives during startup and the optimization.. The web runs well through the machine but the winder is not slowing down quick enough.. The setpoint adder counts for ratio are correct but the drive speed doesn't tick down fast enough as the roll builds..

Questions:

Do I need to send torque setpoint to the slave drives from the master even though I am running the two slaves on a ratio to the master.. For example, the master encoder is sent to both slaves.. Each slave adjusts the ratio to the master speed to run their speed..

Should I put a filter of 1ms on the encoder signal on the master+slaves? Just wondering if I calm down the reference, it may stabilize things.. I was wondering if the reference deviation may cause my issue with the winder not slowing down fast enough?

One of the slaves is a winder and I am seeing the drive not respond to the setpoint adder ratio like it should.. We have another older (exact)machine that we were monitoring and it seemed to respond better to counts. The machine we monitored is the same exact process machine with older drives....For example, the older system sends a ratio of 1-2 == 16383-32767 to the adder block.. When the counts are 19448 RPM == 288, Counts 17364  RPM== 234.. It seems that when we review the new sinamics s120, it appears that even though our counts are changing the same, the speed isn't reducing like it should.. The ratios from the plc are correct but it seems our surface speed doesn't reduce fast enough for our buildup..

The winder ratio is derived from calculations to determine the correct surface area speed.. I have reviewed the calculations and they are the same in the old system vs new system.. It just seems that as the drives run and the roll builds, the same ratio in the new sinamics s120 doesn't slow the drive down fast enough.. I have checked at the scaling is 16383-32767 so all that is correct.. I would have thought at a .998767 ratio in the old system would be the same with the new.. However, I do see some speed variation so that may be my issue.. The speed does tick down with counts but they are not the same as the old system.. I need the drive to tick the same because all the plc code calculations are correct for drive ratios..

I was looking at the extended setpoint generator with setpoint tracking? Would this help?

Any suggestions would be appreciated..