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When an axis POSITIONROLLOVERENABLE flag is set (ON), it means the axis is rotary (i.e., the position coordinates of the axis are periodical). POSITIONROLLOVER defines the period (the length of one revolution in user units) of the axis. POSITIONROLLOVERMIN defines the lower limit coordinate of the revolution. For example:
- POSITIONROLLOVERENABLE = 1
- POSITIONROLLOVERMIN = -180
- POSITIONROLLOVER = 360
The position command of the axis will run between –180 and +180 degrees. If we move by one degree in positive direction from 180 the PCMD value will be -179. Remember to set this value if working with SCARA type robots. Normally, a four degrees of freedom SCARA robot will have set this flag on all the axes except the third when working with XYZR point type.
An additional feature, WRAP selects the trajectory of the movement. If wrap is set, the shorter path is selected. If it is zero, the direction of the path will be the direction between the given target point coordinate and the initial position of the movement.
In relative movements (ABS=0) WRAP is reset and only the movement in a given direction (defined by target-start) is made. In case of relative movement, the above mechanism is not available. An error occurs if the target position exceeds the limits.
When the target point of the movement exceeds the position limits of the axis (PMAX, PMIN), the target coordinate of another roll-period is chosen.
<axis name>.PositionRolloverMin = <value>
Read/Write, Configuration, Task, Terminal
- The POSITIONROLLOVERMIN value may be changed only when the axis is disabled.
- To set the value within a task, the motion element must be attached to that task (using the ATTACH command).
A1.PositionRolloverMin = -180
A1. PositionRollover = 360
- coordinates are between -180 and 180 degrees