Multi-Axis Coordinated Motion Instructions
Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018 403
For the Error Code 54 – Maximum Deceleration Value is Zero, if the Extended
Error returns a positive number (0-n) it’s referring to the offending axis in the
coordinate system. Go to the Coordinate System Properties General Tab and look
under the Brackets ([ ])column of the Axis Grid to determine which axis has a
Maximum Deceleration value of 0. Click on the ellipsis button next to the
offending axis to access the Axis Properties screen. Go to the Dynamics tab and
make the appropriate change to the Maximum Deceleration Value. If the
Extended Error number is -1, this means the Coordinate System has a Maximum
Deceleration Value of 0. Go to the Coordinate System Properties Dynamics Tab
to correct the Maximum Deceleration value.
MCCD Changes to Status Bits:
For the Master Driven Speed Control (MDSC) function, when the MCCD is
executed (goes IP), the CalculatedDataAvailable (CDA) status bit is cleared (as
specified by the Scope variable of the MCCD instruction), in each MCLM and
MCCM instruction tag, which indicates that the Event Distances has been
computed. (The Scope variable specifies either the Active Motion instruction or
Active Motion and Pending instruction (that is, all instructions, in the queue)).
After the MCCD is complete and the Event Distances have been recomputed, the
CalculatedDataAvailable status bit is set again. Therefore, look at the
CalculatedDataAvailable status bit after the MCCD instruction has been
completed to determine when to use the recomputed Event Distances.
If a MCCD is executed (goes IP), the CDA bit is cleared. The Calculated Data for
the move is recomputed using the new dynamics parameters. The CDA bit is set
again when computations are complete. The Calculated Data that is recomputed
is measured from the original Motion Start Point (MSP) to the Event Distance
point using the new dynamics parameters as changed by the MCCD instruction -
not from the point of the MCCD.
Note that if the MCCD changes the speed to 0, the Event Distance is not
recomputed; the CDA bit is not set. The Event Distance is however recomputed if
a second MCCD is issued to restart the motion. The recomputed Calculated Data
includes the duration of the stopped motion.
If the Event Distance is set to 0, the Calculated Data is set to equal the position
that equals the length of the move. This may be one or two coarse update periods
before the PC bit is set because of an internal delay. The end position is typically
achieved in the middle of a coarse update period, which adds up to one additional
coarse update period to the delay. Therefore, if the master is moved a distance
equal to the Calculated Data, you must wait up to 2 iterations more for the PC bit
of the slave move to be set.
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