80
6250 Servo Controller User Guide
M axi m u m A ccel / D ecel C o m m an d s:
C o m m an d
F u n ct i o n
A ver ag e ( S- C u r ve) A ccel / D ecel C o m m an d s:
C o m m an d
F u n ct i o n
A
Acceleration
AA
Average Acceleration
AD
Deceleration
ADA
Average Deceleration
HOMA
Home Acceleration
HOMAA
Average Home Acceleration
HOMAD
Home Deceleration
HOMADA
Average Home Deceleration
JOGA
Jog Acceleration
JOGAA
Average Jog Acceleration
JOGAD
Jog Deceleration
JOGADA
Average Jog Deceleration
JOYA
Joystick Acceleration
JOYAA
Average Joystick Acceleration
JOYAD
Joystick Deceleration
JOYADA
Average Joystick Deceleration
LHAD
Hard Limit Deceleration
LHADA
Average Hard Limit Deceleration
LSAD
Soft Limit Deceleration
LSADA
Average Soft Limit Deceleration
PA
Path Acceleration
PAA
Average Path Acceleration
PAD
Path Deceleration
PADA
Average Path Deceleration
The command values for average accel/decel (
AA
,
ADA
, etc.) and maximum accel/decel (
A
,
AD
,
etc.) determine the characteristics of the S-curve. To smooth the accel/decel ramps, you must
enter average accel/decel command values that satisfy the equation
1/2 A
max
≤
A
avg
< A
max
,
where
A
max
represents maximum accel/decel and
A
avg
represents average accel/decel. Given
this requirement, the following conditions are possible:
❏
If
A
avg
> 1/2 A
max
, but A
avg
< A
max
, you have achieved an S-curve profile with a variable
period of constant accel/decel (see drawing below).
❏
If
A
avg
= 1/2 A
max
,
you have achieved what is called a Pure S-curve profile in which there is no
period of constant accel/decel and jerk is at an absolute minimum (see drawing below).
T
T
S-Curve (A
avg
> 1/2 A
max
)
V
A
A
max
A
avg
AD
max
AD
avg
T
T
Pure S-Curve (A
avg
= 1/2 A
max
)
V
A
A
max
A
avg
AD
max
AD
avg
AD
AD
❏
Once you enter an
A
avg
value that is
≠
zero and satisfies
1/2 A
max
≤
A
avg
<
A
max
, S-curve
profiling is enabled, but only in the operation that uses that particular
A
avg
command. For
example, entering a
HOMAA
command enables S-curve acceleration profiling only for homing
moves, not for other functions such as jogging (which would require the
JOGAA
command). To
return to the default trapezoidal profiling mode, enter an
A
avg
value of zero, or set
A
avg
= A
max
.
❏
If
A
avg
= A
max
,
a trapezoidal profile results, but can be changed to an S-curve by specifying a
new
A
avg
value less than
A
max
, or set
A
max
greater than
A
avg
.
❏
If
A
avg
< 1/2 A
max
, or A
avg
> A
max
,
when you try to initiate motion, the move will not be
executed and an error message,
*INVALID CONDITIONS FOR S_CURVE ACCELERATION—
FIELD
n
, will be displayed.
❏
If
A
avg
= zero
or if you never enter an
A
avg
command, the 6250 defaults to trapezoidal profiling
and the
A
avg
command value will always match the
A
max
command value. However, if you enter
an
A
avg
deceleration of zero, you will receive the error message
*INVALID DATA—FIELD n
,
where
n
is the number of the data field.
❏
If you never enter the maximum (
A
max
) or average (
A
avg
) decel command values (
AD
or
ADA
,
HOMAD
or
HOMADA
, etc.), the average decel value will always match, or track, the average accel
value (
AA
,
HOMAA
, etc.). However, once you change the maximum decel, the average decel will
no longer track the average accel.
