In industrial fields like textile, paper and plastic film working, the holding of material in axis, stretching or relaxation is necessary.
System has to keep the stream from the decoiler to the coiler constant (in axis, stretching or relaxation).
Coiler speed is controlled by Master inverter. Slave 1 and 2 adjust dragging in axis, stretching or relaxation of material. Their speed depend upon Master speed (managed by serial bus from PL250) and ratio % of streaming (this ratio can be changed by touch screen TD320).     
Decoiler brake/friction command is regulated by PL250 0…10Vdc analog output with servo-diameter regulation algorithm and line speed read by serial bus.
Slave 3 coiler couple control is regulated by PL250 with serial bus RS485.

Direct strength control regulation option

It’s possible to improve system regulation with the real strength control applying to Master roller a couple of high dynamic load cell type LFED with integrated support for rolling bearing.
In this option roller Slave 1 and 2 are motorless, while coiler speed is controlled by serial bus from PL250 directly.   
The two LFED load cell are directly read by PL250 and it controls electric axis between Master roller and coiler, while PID algorithm controls decoiler brake/friction strength to hold roller traction setpoint constant.