Hello,

let me answer you questions as following.

a) Difference between Set and actual length ( This is not length variation ) 

A difference between set and actual length could have a lot of (complex) reasons.
Here are some of them.

• Diameter of the measuring wheel (already checked)
• Any slippage of the measuring wheel excluded?
• Correct diameter / flying circle of the knife cylinder entered?
• Resolution of the measuring wheel encoder high enough?
• Evtl. some digits of the gear factor have been truncated?

Could you please provide some more information for further evaluation..
? What type of Rotary Knife are you working with?
? What material should be cut?
? Which profile within the synchronous range did you select?
? Is the deviation between set and act. value dependent on the line speed?

b) ... "Actual Value with Extrapolation" ... / RK trips on rotation

This "Actual Value coupling with Extrapolation" requires an individual Time Constant.
Setting the Time Constant too aggressive cause controller overshoots. Setting the T.C. too weak leads to significant controller deviation.
The SCOUT CD provides an "Extrapolation Time Calculation Tool".

? Did you adjust filters for the Actual Value coupling with Extrapolation?
? Do you know this Extrapolation Time Calculation Tool?

As the answers to this complex problem won't be simple ones a straight contact to the Siemens
Converting Motion Control specialists for deeper evaluation would be quite fruitful.
Please note following email address for your convenience:

With best regards,
St_Karl