534 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018
MDSC Lock Direction Parameter Description
Input
Parameter
Data Type Description Value
Lock Direction Immediate This parameter is used for both Time Driven and
Master Driven mode. In master driven mode the Lock
Direction is used by the axis specified as the Master
Axis in the MDAC instruction. It is not used in Time
Driven mode.
The first word of the Lock Direction (Immediate or
Position) enumeration definition identifies the lock
type as either:
• Immediate (lock is per formed immediately)
• Position (lock is per formed when the Master Axis
crosses the specified Lock Position)
The second word of the Lock Direction (For ward or
Reverse) specifies the direction in which the Master
Axis has to be moving when it crosses the Lock
Position for the lock to take effect.
Forward is positive velocity, reverse is negative
velocity. The instruction will error with
MDSC_LOCKDIR_CONFLICT (95). The enumeration
NONE must be used in time driven mode or the
instruction errors. On of the other 4 enumerations
must be used in master driven mode.
For an MAM instruction, the Slave always moves in one
direction -- the programmed direction. Once it starts
moving it follows the Master Axis in the programmed
direction, regardless of the direction of the Master
Axis. If the Master reverses, the slave stops.
These are the Master Driven mode enumerations.
Default = 0
0 = None
1 = Immediate For ward Only
2 = Immediate Reverse Only
3 = Position For ward Only
4 = Position Reverse Only
Enumeration Descriptions for the MDAC Input Parameter
Enumeration Name Description
0 None Indicates that the Lock Position is not active. If Lock Direction is set to None and the Master Driven
mode is selected by the speed parameter of the motion instruction, a run time error is generated.
If Lock direction is set to a value other than None and the speed parameter units indicate Time
Driven mode, an error is also generated.
1 Immediate
Forward Only
Motion star ts immediately when the Master is moving in the For ward Direction. The Master Axis is
followed only while it is moving in the Forward Direction.
2 Immediate
Reverse Only
Motion starts immediately when the Master Axis is moving in the Reverse Direction. The Master Axis
is followed only while it is moving in the Reverse Direction.
3 Position
For ward Only
Motion star ts, for example, the Slave locks to the Master Axis when the Master Axis crosses the Lock
Position while it is moving in the For ward Direction. The Master Axis is followed only while it is
moving in the For ward Direction. If the start position of the Master Axis equals the Lock Position
and this enumeration is selected, then motion does not start because the Lock Position is not
crossed.
4 Position Reverse
Only
Motion sta ts when the Master Axis crosses the Lock Position while it is moving in the Reverse
Direction. The Master Axis is followed only while it is moving in the Reverse Direction. If the start
position of the Master Axis equals the Lock Position and this enumeration is selected, then motion
does not start because the Lock Position is not crossed.
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