Siemens Sinumerik 840DiE sl - Page 438

01/2007
14.4 Frequency response measurements
14-438
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
S Averaging
The accuracy of the measurement and measurement duration increase with
this value. A value of 20 is normally suitable.
S Settling time
This value represents the delay between recording of the measured data
and injection of the test setpoint and offset. A value of between 0.2 and 1 s
is recommended. Do not set too low a value for the settling times or the fre-
quency response and phase diagrams will be distorted.
S Offset
The measurement requires a slight speed offset of a few motor revolutions
per minute. The offset must be set such that no speed zero crossings occur
at the set amplitude.
The transient or positioning response of the position control in the time range,
and in particular the effect of setpoint filters, can be assessed with the step and
ramp stimulation functions.
Possible measured variables:
S Position actual value (active position measuring system)
S Control deviation (following error)
Measuring parameters
S Amplitude
Determines the magnitude of the specified setpoint step change or ramp.
S Measurement time
This parameter determines the period of time to be recorded (maximum:
2048 position controller cycles).
S Settling time
This value represents the delay between measured data recording/test set-
point output and the injection of the offset.
S Ramp time
The position reference value is specified with the ”Setpoint ramp” basic
measurement according to the set ramp time. In this case, the acceleration
limits which currently apply to the axis or spindle are effective.
A jerk–controlled motion can be set for a specific axis with:
– MD 32400 AX_JERK_ENABLE (axial jerk limitation) =1
– MD34210 AX_JERK_TIME (time constant for the axial jerk filter).
The position setpoint and the actual value of the active measuring system
are recorded in each case.
S Offset
The step is stimulated from standstill or starting from the constant traverse
speed set in this parameter.
If an offset value other than zero is input, the step change is stimulated dur-
ing traversal. For the sake of clarity, the displayed position actual value does
not include this speed offset.
Measurement:
Setpoint step
change and
setpoint ramp
14 Drive O
p
timization with HMI Advanced