MC1151A PMD, MC1151A Datasheet - Page 20

• Manufacturer Part Number: MC1151A
• Description: (MC1x51A) Advanced Step Motor Control Chipset
• Manufacturer: PMD

will occur, and all new parameters will be ignored except the
position. See the section of this manual entitled "Command Error"
for more information..
Before switching to the S-curve point to point profile mode, the
axis should be at a complete rest.
When the axis is in the S-curve profile mode, the SET_MAX_ACC
command should be used to load the max. acceleration value. The
alternate acceleration loading command SET_ACC can not be
used.
Trapezoidal Point to Point
The following table summarizes the host specified profile parameters
for the trapezoidal point to point profile mode:
Profile
Parameter
Destination
Position
Maximum
Velocity
Starting
Velocity
Accel.
In the trapezoidal point to point profile mode the host specifies a
destination position, a maximum velocity, a starting velocity, and an
acceleration. The trajectory is executed by accelerating at the
commanded acceleration, beginning at the starting velocity, to the
maximum velocity where it coasts until decelerating such that the
destination position is reached with the axis at rest (zero velocity). If it is
not possible to reach the maximum velocity (because deceleration must
begin) then the velocity profile will have no "coasting" phase. The
acceleration rate is the same as the deceleration rate.
A new maximum velocity and destination position can be specified
while the axis is in motion. When this occurs the axis will accelerate or
decelerate toward the new destination position while attempting to
satisfy the new maximum velocity condition.
Before switching to the Trapezoidal point to point profile mode,
the axis should be at rest.
When in Trapezoidal point to point profile mode, to change the
acceleration, the axis must come to a complete stop. After this has
occurred, a new acceleration value can be loaded. If the
acceleration parameter is changed during motion then a
'command error' will occur, and all updated parameters will be
ignored except the position. See the section entitled 'Axis Status
for more informaton' on command errors.
The Starting Velocity can not be changed while the axis is in
motion.
Representation & Range
signed 32 bits
-1,073,741,824 to 1,073,741,823
unsigned 32 bits (1/2 16 scaling)
0 to 1,073,741,823
unsigned 32 bits, (1/2 16 scaling)
0 to 1,073,741,823
unsigned 32 bits (1/2 16 scaling)
0 to1,073,741,823
Units
steps
steps/cycle
steps/cycle
steps/cycle 2
20
The following figure shows a velocity profile for a typical point to point
trapezoidal move, along with a more complicated move involving on the
fly changes to the maximum velocity and the destination position.
Velocity Contouring
The following table summarizes the host specified profile parameters
for the Velocity contouring profile mode:
Profile
Parameter
Maximum
Velocity
Starting
Velocity
Acceleration
Vel.
Vel.
starting
velocity
* negative numbers using 1/2 16 scaling are handled no
differently than positive numbers. For example if an
acceration value of -1.95 steps/cycle 2 is desired, -1.95 is
Trapezoidal Profile With Non-Zero Starting Velocity
Vel.
change max
velocity
Complex trapezoidal mode motion
Simple trapezoidal mode motion
Representation & Range
unsigned 32 bits (1/2 16 scaling)
0 to 1,073,741,823
unsigned 32 bits, (1/2 16 scaling)
0 to 1,073,741,823
signed 32 bits* (1/2 16 scaling)
-1,073,741,824 to 1,073,741,823
change max
velocity
change destination
change destination
position
position
Units
steps/cycle
steps/cycle
steps/cycle 2
Time
Time
Time