User`s manual

SECTION 5: DS2100 FUNCTIONAL OVERVIEW DS2100 User's Manual
C27750-001 PAGE - 5-23 -
5.6.1.2 Encoder types
There are various encoder types supported. They are selected with the parameter encoder_type
(index 0x2e20,
subindex 2). It can have the following values:
0 - no encoder connected
1 - Digital incremental encoder
2 - Analogue incremental encoder with two analogue sinusoidal quadrature
output signals with 1 Vpp amplitude
3 - SSI interface absolute singleturn or multiturn encoder
4 - Stegmann Hiperface interface absolute encoder
5 - Heidenhain EnDat 2.1 interface absolute encoders
Depending on the encoder type selected there are more parameters that have to be initialised in order to allow
encoder operation.
5.6.1.3 Number of increments
For normal digital, analogue or SSI interface encoders (encoder_type 1..3) the parameter
encoder_number_of_increments
(index 0x2e20, subindex 3) has to be set to the number of increments (optical lines)
per mechanical revolution. If the encoder is used for motor commutation only powers of 2 are allowed for
encoder_number_of_increments
(i.e. 512, 1024, ...). When a Hiperface or Endat encoder is connected this
parameter is obtained from the encoder. In this case encoder_number_of_increments
is read only.
5.6.1.4 Encoder Position
The parameter encoder_position
(index 0x2e20, subindex 10) contains the 32-bit encoder position. It is assembled
using the encoder incremental count value, an interpolated analogue value (only when using encoders with analogue
output signals) and an overflow counter that counts the full revolutions of the encoder.
5.6.1.5 Encoder resolution
For encoders with analogue sinusoidal signals the incremental steps can be interpolated to achieve higher resolution
and better velocity signals. The resolution is user selectable using the parameter encoder_resolution
(index 0x2e20,
subindex 5). It determines the bit position of the full encoder increments in the encoder position encoder_position
.
The minimum value is 2 because of 4 incremental steps per optical encoder line using every transition in the
quadrature signal. The reasonable maximum for encoder_resolution
is about 12. Values above that can be used to
change the scaling of the encoder position value but doesn't increase the available resolution any more. Please note
that the absolute accuracy still largely depends on the accuracy of the analogue encoder signals.
5.6.1.6 Encoder Offset
To compensate for a mechanical misalignment between the encoder and the desired encoder position, the parameter
encoder_offset
(index 0x2e20, subindex 9) can be used. Setting it to the value of encoder_position at a certain
position will zero the encoder position output value encoder_position
.