Multi-Axis Coordinated Motion Instructions
Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018 499
Changing the motion mode between Master Driven and Time Driven Mode and
vice versa is automatically performed when another motion instruction (such as,
MCLM and MCCM) is activated if the new instruction has been programmed in
a different mode than the active motion instruction.
When the new motion instruction is activated, the system will assume that the
desired mode for the new instruction is the mode (Master Driven or Time
Driven) as specified in the programmed units of the speed parameter contained in
the new instruction. At all times, including when changing modes, the Accel,
Decel, and Jerk must be programmed in the same units as the Speed parameter or
the instruction will get a MDSC_UNITS_CONFLICT_ERROR error.
A runtime MDSC_INVALID_MODE_OR_MASTER_CHANGE error will
occur if you attempt to change from Master Driven Mode to Time Driven Mode
or vice versa with an MCCD instruction.
If both the master and slave axes are idle (for example, paused), the MCLM or
MCCM can make a change on the slave. However, the error MDSC
IDLE_MASTER_AND_SLAVE_MOVING is generated if MDSC mode is
started while the Slave Coordinate System is moving when the master is idle.
Different Time Driven and Master Driven Modes may be used for different
motion types for superimposed motion. For example, the MAM may be in time
drive mode for an axis in the Coordinate System and the MCLM may be in
Master Driven Mode for the Coordinate System.
Change the Master Axis
The following sequence of events must be followed to transfer a Slave Coordinate
System from one Master Axis to a second Master Axis.
• First, you must execute an MDCC instruction to reassign the Slave
Coordinate System from the first Master Axis to the second Master Axis.
This makes the reassignment pending. The IP bit of the MDCC instruction
is set as an indication of the pending reassignment.
• Second, you must execute a new motion command (for example, an MCLM
or MCCM). The Slave Coordinate System becomes unlocked from the first
Master Axis and reassigned to the second Master Axis when this motion
instruction is executed (goes IP).
The final effective slave speed is computed as the product of the Master Axis’
speed and the slave’s programmed speed. If the new final effective Slave
Coordinate System speed is less than 10%, depending on the move of the original
Slave Coordinate System speed, then the change will not be allowed and the
MDSC_INVALID_SLAVE_SPEED_REDUCTION error will occur. If the
second Master Axis is idle (velocity=0), the motion instruction making this
request receives an MDSC_IDLE_MASTER_AND_SLAVE_MOVING error.
Change between master driven
and time driven modes for
Coordinated Motion
instructions
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