This is where modulo positioning comes into its own. The term "modulo" is borrowed from
mathematics:
The modulo finds the rest after dividing two numbers. A simple example: (9 mod 4) is
equal to 1, because if 9 is divided by 4, the remainder is 1.
Modulo positioning is an endless positioning in a circle and is used in applications where
the motor position must be counted cyclically. The motor position is calculated with a
complete mechanical rotation of the load. Depending on the application, the following
modulo motion types are possible, which are defined in object Position Range Limit Des-
ignation (2400h)
Ä
Chap. 15.7 ‘PROFIdrive Position Mode’ page 555:
n optimized (shortest way)
n Rotation only in negative direction
n Rotation only in positive direction
Limit values (607Bh)
Ä
Chap. 15.7 ‘PROFIdrive Position Mode’ page 555 can be used
to define the positions at which the position overflow occurs. If the maximum number of
encoder rotations is exceeded, an overflow occurs and the encoder starts counting again
from zero (depending on whether "0...360" or "-1800...1800" has been defined). Modulo
positioning stores this overflow and ensures that no position information is lost.
Modulo positioning is possible regardless of the axis type, i.e. it can be used for both
linear and rotary axes. A modulo axis has a consecutive absolute position in the range of
±∞. The modulo position of the axis is merely additional information about the absolute
axis position. Modulo positioning represents the desired target position in a different way
than absolute positioning (where the user clearly defines the target).
Within a system, a rotary axis performs an operation. The starting position for each
operation is 90° and with each cycle the axis must be positioned 360° in the positive
direction.
The position of the axis is reset to the initial value once the modulo length has been
exceeded. For a rotary axis with a modulo length of 0° to 360°, the axis position starts at
zero again when 359° is exceeded, i.e. position 0°=360°.
Example
Rotary Applications may e.g. be performed by Modulo Positioning functions:
n Shortest route (2400h|00 = 1)
n Always positive direction (2400h|00 = 2)
n Always negative direction (2400h|00 = 3)
n Position Range: 1 Revolution
n User Unit Configuration: 0.1 deg
1. Disable Software Position Limits
n 607Dh|00 Software Position Limit – Min: 8000 0000h
n 607Dh|01 Software Position Limit – Max: 7FFF FFFFh
2. Enable Position Range Limits
n 607Bh|00 Position Range Limit – Min: 0
n 607Bh|01 Position Range Limit – Max: 3600
3. Enable Absolute Target Command In Positioning In Range Mode Execution
n 2538h|00 MDI_MOD - 1 (Absolute Target Command)
Configuration example
Value range of corresponding target / actual values
n Target Position (607Ah): 8000 0000h to 0 to 7FFF FFFFh
n Position Actual Value (6064h): 8000 0000h to 0 to 7FFF FFFFh
Fig. 365: R-250 1-station
positioner with a vertical
rotary axis
Rotary Applications (e.g.
Rotary Table)
Sigma-7 Series SERVOPACKs
PROFIdrive Drive Profile
PROFIdrive Position Mode > Modulo Positioning
| | PROFINET Communications - SIEP YEUOC7P 02A Revision 0 | en | 510
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