550 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018
The following table describes the predefined data type status bits for motion
instruction MAM, MATC, and MAJ.
Status Bits for Motion Instructions when an MDAC Instruction is Active
Bit Description
.EN (Enable) The Enable bit is set when the rung makes a false-to-true transition and remains set until the servo message transaction is completed and the rung
goes false.
.DN (Done) Timing done output. Indicates when the accumulated time is greater than or equal to the preset value.
.ER (Error) The Error bit is set to indicate that the instruction detected an error, such as if you specified an unconfigured axis.
.PC (Process Complete) The Process Complete bit is set after the diagnostic test process has been successfully completed.
.IP (In Process) The In Process bit is set on positive rung transition and cleared after the diagnostic test process is complete, or terminated by a stop command,
shutdown, or a servo fault.
.AC (Active) The Active bit is set when a move (MAJ, MAM or MATC) goes IP in Master Driven mode on the axis that is selected as the Slave Axis of the MDAC
instruction. The AC bit will be reset when all single axis motion that is being controlled by the MDAC is completed. If the Slave Axis is star ted in
Time Driven mode, then the AC bit of the MDAC does not go active. The IP bit of the MDAC instruction does not change at this
time.
ACCEL The ACCEL bit is set as expected during motion. It is independent of Master Axis acceleration.
The ACCEL bit on the instruction driving the Slave Axis, for example, MAM on the Master Axis is set as the Slave Axis accelerating to its commanded
speed as a result of the master axis acceleration. In addition, The ACCEL bit of the slave axis is set when it is accelerating due to not being at the
programmed acceleration. This bit is insensitive to acceleration occurring on the Master Axis. However, the AccelStatus bit, which is in the
MotionStatus word of the Slave Axis (not the instruction driving the slave axis), is set or cleared based on changes in the programmed velocity of
the Slave Axis.
DECEL The DECEL bit is set as expected during motion. It is independent of Master Axis deceleration.
The DECEL bit on the instruction driving the Slave Axis is set as the Slave Axis is decelerating to its commanded speed. as a result of the master axis
deceleration. In addition, The DECEL bit of the slave axis is set when it is decelerating due to not being at its programmed deceleration. This bit is
insensitive to deceleration occurring on the Master Axis.
However, the DecelStatus bit, which is in the MotionStatus word of the Slave Axis (not the instruction driving the slave axis), is set or cleared based
on changes in the programmed velocity of the Slave Axis.
TrackingMaster Indicates that the Slave Axis is tracking the Master Axis. Only used in Master Driven mode.
When an instruction is initiated in Master Driven mode, the Slave Axis accelerates to the speed that its programmed for MDSC mode. This bit is
insensitive to slave acceleration/deceleration of the master axis. The Tracking Master is set when the acceleration is complete in MDSC mode. This
means that the Slave Axis is synchronized to the Master Axis. This bit is insensitive to the accel/decel of the master axis.
The Tracking Master bit is cleared when any of the following occurs on the Slave Axis:
• When the Slave Axis star ts to either accelerate or decelerate for any reason, for example, for an MCD or an MAS being issued.
• When the Slave Axis is relinked to another Master Axis. In this situation, the TrackingMaster bit is first cleared and then it is set again in the new
instruction status word when the Slave Axis starts tracking the new Master Axis again.
• The Slave Axis is stopped. The Tracking Master is cleared as soon as the stop is initiated on the Slave Axis.
This bit is never set when LockDir = NONE. The Tracking Master bit on the Slave Axis is not affected by any operation (for example, MAS, MCD) on
the Master Axis. The Tracking Master bit is always cleared in Time Driven mode.
CalculatedDataAvailable Indicates when the output data in the Calculated Data parameter has been updated and is available.
The CalculatedDataAvailable bit is not set for any move that Event Distance is not specified, that is, for any move where the Event Distance
parameter in the instruction is zero, this is not the value in the parameter array.
Instructions (MAM, MATC,
MAJ) When MDAC Is Active
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