NORD Drivesystems BU0510 - Manual (Page 22)

POSICON position control for NORD frequency inverters, SK 530E and above
22 Subject to technical alterations BU 0510 GB-3911
The reference point run can be cancelled by removing the "Enable" signal or by "Emergency Stop" or "Block
Voltage".
NOTE
In this case the frequency inverter does not generate an error message.
For further details of the possible functionality settings, please refer to the relevant parameter description in
Section 4 Parameter settings.
3.2.1.2 Reset position via digital inputs or BUS I/O In Bits
tAs an alternative to a reference point run, one of the digital inputs can be programmed to the setting "Reset
Position" (P420-P425 or P470, setting 61). Control via one of the Bus IO Bits is correspondingly identical. In
contrast to the reference point function, the input or the Bus IO Bit is always effective and when the signal
changes immediately sets the actual position from 0
→ 1 to 0. If an offset has been parameterised in
parameter P609 "Offset Position", the axis will be displaced by this value. Resetting of the position is carried
out independently from the setting of the "Positioning" in parameter P600. In "Position Setpoint Mode" the
setpoint position (in parameter P610, 1 = Position increment array) is set to 0.
The precision of reproducibility of the referencing via Reset Position is not as good as with the reference point
run - as it depends on the tolerance of the reference point switch and the speed with which the switch is
approached. However, the precision achieved is sufficient for many applications. In addition, referencing can
be performed without interrupting the positioning.
The function "Reset Position" can also be realised via a serial interface or the Bus IO In Bits. For this, one of
the bus setpoint values (P546, P547 and P548) must be set to 17 "Bus IO In bits 0...7" and under P480
"Function Bus I/O In Bits" the function setting 61 must be assigned to the corresponding bit.
For further details of the possible functionality settings, please refer to the relevant parameter description in
Section 4.
3.2.2 Position detection with absolute encoders
The absolute encoder transfers the actual position value to the frequency inverter in digital form. The position
is always completely available in the absolute encoder and is also correct after displacement of the axis when
the inverter is switched off. A reference point run is therefore not necessary.
If an absolute encoder is connected, the parameter P604 "Encoder Type" must be parameterised to one of the
absolute functions (Setting 1 or 5-15) of the relevant absolute encoder.
The resolution of the encoder is set in parameter P605.
Parameter Meaning
P605[-01] Multi-turn Number of bits of rotations
P605[-02] Single-turn Number of bits per one revolution
P605[-03] Sin/Cos periods, Hiperface Number of bits for Sin/Cos periods per rotation
Table 12: Parameter P605 - Selection of encoder resolution for absolute encoders