Control Techniques Nidec SI-EtherCAT User Manual page 70

7.3.12 Profile units
The SI-EtherCAT implementation provides a means to convert profile units into position controller
and drive units. All scaling values are standard profile objects. The following objects are supported:
Table 7-25 Supported profile units
Index
0x608F
0x6091
0x6092
The initial value of the feed constant object (0x6092) shall be calculated from the normalization
turns parameter of the associated encoder channel if the default values have not been modified.
If either value is non default the values will be taken as is.
For positions, the scaling control will include a feed constant, a gear ratio and an encoder
resolution. These values will be combined together to scale the drive position (i.e. encoder
increments) to position in user-defined unit by the following formula.
user defined unit position
It will be possible to change these values non-cyclically (i.e. using SDOs), It will not, however, be
possible to change these values cyclically (i.e. by mapping PDOs to them).
These scaling objects will be combined together to scale drive velocities (i.e. encoder increments
per second) to velocity in user-defined unit by the following formula.
user defined unit velocity
It will be possible to change these values non-cyclically (i.e. using SDOs). It will also be necessary
to re-scale velocity limit values with the new factor. It will not be possible to change these values
cyclically (i.e. by mapping PDOs to them)
The position encoder resolution object 0x608F will be read-only and its value will be derived from
drive parameter values. The numerator of 0x608F will be derived from the normalization turns
parameter of the associated encoder channel. The denominator of 608F will be always 1.
The user-defined position and velocity values will be handled in signed 32-bit values. The scaled
position will rollover the boundary if it is too large.
When the gear ratio or the feed constant is applied, the combination of
feed constant
--------------------------------------------------------------------------------------------------------
position encoder resolution gear ration
to the AMC slave user unit's ratio and its inverse value will be put in the AMC output user unit's
ratio. To prevent the overflow risk of AMC ratio parameters, before being applied, the size will be
checked to make sure the numerator and the denominator of the combined results are within 1 to
31
2 -1 range. If not, the module will trip with 'Scaling failure' and the AMC scaling ratios will stay
previous value.
The Gear ratio object will not be used for Homing mode.
NOTE
70
position_encoder_resolution
gear_ratio
feed_constant
-------------------------------------------------------------------- -
=
position encoder resolution
--------------------------------------------------------------------------------------------------------
=
position encoder resolution gear ration
will be calculated and simplified. The result will be applied
⋅
Name
⋅
drive position feed constant
⋅
drive velocity feed constant
⋅
gear ratio
⋅
SI-EtherCAT User Guide