➄
Basic 6250 Features
47
As the velocity scaling factor (
SCLV
/
PSCLV
) changes, the velocity command's range and its
decimal places also change (see table below). A velocity value with greater resolution than
allowed will be truncated. For example, if scaling is set to
SCLV1Ø
, the
V9.9999
command
would be truncated to
V9.9
.
SCLV
/
PSCLV
Value
(steps/unit)
Velocity Resolution
(units/sec)
Decimal Places
Max. Velocity
Calculation
1 - 9
10 - 99
100 - 999
1000 - 9999
10000 - 99999
100000 - 999999
1
0.1
0.01
0.001
0.0001
0.00001
0
1
2
3
4
5
200 x
ERES
SCLV
Distance Scaling (
SCLD
)
If scaling is enabled (
SCALE1
), the
D
and
PSET
command values entered are internally
multiplied by the distance scaling factor (
SCLD
). Since the
SCLD
units are in terms of
steps/unit, all distances will thus be internally represented in encoder steps. For instance, if
your distance scaling factor is 10000 (
SCLD1ØØØØ
) and you enter a distance of 75 (
D75
), the
actual distance moved will be 750,000 (10000 x 75) encoder steps or counts.
As the distance scaling factor (
SCLD
) changes, the distance command's range and its decimal
places also change (see table below). A distance value with greater resolution than allowed
will be truncated. For example, if scaling is set to
SCLD4ØØØ
, the
D1Ø5.2776
command
would be truncated to
D1Ø5.277
.
SCLD
(steps/unit)
Distance Resolution (units)
Distance Range (units)
Decimal Places
1 - 9
1
0 -
±
999,999,999
0
10 - 99
0.1
0.0 -
±
99,999,999.9
1
100 - 999
0.01
0.00 -
±
9,999,999.99
2
1000 - 9999
0.001
0.000 -
±
999,999.999
3
10000 - 99999
0.0001
0.0000 -
±
99,999.9999
4
100000 - 999999
0.00001
0.00000 -
±
9999.99999
5
NOTE
FRACTIONAL STEP TRUNCATION
NOTE
If you are operating in the incremental mode (
MAØ
), when the distance scaling factor (
SCLD
)
and the distance value are multiplied, a fraction of one step may possibly be left over. This
fraction is truncated when the distance value is used in the move algorithm. This truncation
error can accumulate over a period of time, when performing incremental moves
continuously in the same direction. To eliminate this truncation problem, set the distance
scale factor (
SCLD
) to 1, or a multiple of 10.
Scaling Example
A user has a 4,000 step/rev motor/drive servo system attached to a 5-pitch leadscrew that he
wants his operator to position in inches (4,000 steps/rev x 5 revs/inch = 20,000 steps/inch).
A scale factor of 20,000 could then be assigned to the distance scale factor (
SCLD
). If the
operator entered a move value of 1.000, the 6250 would command 20,000 encoder steps,
which would correspond to one inch.
The commands below define the units that are used for both axes. The units for position are
20000 and 4000 for axes #1 and #2, respectively. The units for axis #1 enable the user to
program a 4000 step/rev drive with a 5-pitch lead screw in units of inches. Axis #2 uses a
4,000 step/rev drive and allows the user to program in revolutions.
Command
Description
>
SCALE1
Enable scaling
>
SCLD2ØØØØ,4ØØØ
Distance scale factor
>
SCLV4ØØØ,4ØØØ
Velocity scale factor (rps)
>
SCLA4ØØØ,4ØØØ
Acceleration and deceleration scale factor (rps
2
)
