Lenze i700 - Manual (Page 90)

5 Motor control & motor settings
5.9 Setting the feedback system for the servo control
90
Lenze · i700 servo inverter · Reference manual · DMS 1.5 EN · 03/2014 · TD05
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Determination and display of the current angular drift
The value displayed in the
0x2C42:3 object (or 0x3422:3 for axis B) indicates whether too much or
too less pulses, caused by EMC, have been detected by the device-internal counter unit. This value
is detected differently, depending on the encoder type:
In case of an incremental sin/cos encoder, the pulses are counted between two zero pulse events of
the Z track. In an error-free status, this value corresponds to the set number of increments. The
accuracy of this procedure corresponds to a line graduation of the encoder of ± 1. The difference
between set number of increments and counted pulses is converted to an angle with an accuracy of
±0.1°. A disadvantage is that only after one complete encoder revolution, an updated value of the
angular drift is available and thus the update rate depends on the speed.
In case of a sin/cos absolute value encoder with HIPERFACE® protocol, no Z track is available. Here,
instead, the position is regularly read out of the encoder. When the encoder is read out for the first
time (after power-up or removal of an open circuit), the encoder position is used to initialise the
device-internal counter unit and set a device-internal position. All other read-out processes from
the encoder are used to generate a difference between the device-internal position and the encoder
position. In an error-free status, the difference is zero. The accuracy of the process, however, is,
speed-dependent due to the dead time of the communication with the encoder and thus restricted
towards the zero pulse procedure. An advantage here, however, is that the update rate does not
depend on the speed but on the communication rate only. The update rate is encoder-specific and
generally is within the range between 30 ... 50 ms.
An evaluation of the angular drift regarding an error response is not provided in the Servo-Inverter
i700. This has to be carried out in the control system.
Subindex 3: Encoder: Angle drift - Actual angle error
From version 01.03
Display area (min. value | unit | max. value) Initialisation
-3276.8 ° 3276.7
 Write access  CINH  OSC  P  RX  TX Scaling: 1/10 INTEGER_16
Subindex 4: Encoder: Signal quality - Actual amplitude
From version 01.03
The signal quality indicates the actual amplitude of the SinCos analog signals with regard to 1 Vss = 100 %.
• In case of higher-order drives, the signal quality should be between 95 % and 105 %.
• There is no need for optimisation if the signal quality is within the tolerance zone for the analog encoder signals
given in the data sheet of the encoder manufacturer.
Display area (min. value | unit | max. value) Initialisation
0 % 255
 Write access  CINH  OSC  P  RX  TX UNSIGNED_8