Multi-Axis Coordinated Motion Instructions
Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018 357
Master Reference
The Master Reference for an MDCC instruction selects the Master Axis position
source.
The enumerations for Master Reference Axis are:
Actual – Slave motion is generated from the actual (current) position of the
Master Axis as measured by its encoder or other feedback device.
Command – Slave motion is generated from the command (desired) position of
the Master Axis. Because there is no Command Position for a Feedback Only
Axis, if you select either Actual or Command for Master Reference, the Actual
Position of the Master Axis is used. The Actual and Command Position are always
the same for this case. No error is generated. Because there is no Actual Position
for a Virtual axis, if you select either Actual or Command for Master Reference,
the Command Position is used. No error will be generated.
An error is generated if a MDCC instruction is executed that changes the Master
Reference of a Slave Coordinate System that is in motion. The new MDCC
instruction will error and the original one will remain active.
Nominal Master Velocity
If master driven coordinated move is programmed to run at a speed that equals
100% of maximum and master axis runs at its Nominal Master Velocity, then the
coordinated move will run at the configured maximum speed of the coordinate
system.
Calculate actual master axis velocity in percentage of the maximum as a percentage
of actual master velocity with respect to nominal master velocity. For example,
nominal master vel =50 ips therefore actual vel = 40 ips = (40/50) * 100 = 80%.
Calculate actual slave velocity in a percentage of the maximum as a product of
programmed slave velocity in the percentage of the maximum and actual master
axis velocity percentage of the maximum. For example, programmed slave velocity
= 50% of the maximum, master velocity = 80% of the maximum, final slave
velocity = 80 * 50 = 40% of the maximum.
Convert final slave velocity in a percentage of maximum to Units/sec as usual. For
example, final velocity = 40%, coordinate system maximum is speed 200
Units/sec, final velocity limit is 200 * (40/100) = 80 Units/sec.
Structured Text
See Structured Text Syntax for more information on the syntax of expressions
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