Installation guide

Keyword Reference Guide
MN1270 02.2002 79
Attributes:
Controller Read Write Command Multi-
Axis
Scaled Default Range
NextMove
   
40000,
1000
0.0 ≤ x ≤ 8388607.0
Description:
For a positional move, the motion profile is specified by the acceleration (
ACCEL), deceleration
(
DECEL) and the slew speed. The SPEED and FEEDRATE keywords operate identically; both set the
slew speed for a positional move. The way in which the slew speed is interpreted is controlled with the
FEEDRATEMODE keyword.
In ‘speed mode’ (as set with the
FEEDRATEMODE keyword), the FEEDRATE is applied to all positional
moves, including those already in the buffer. In ‘feedrate mode’ the
FEEDRATE only applies to new
moves loaded into the move buffer. Moves already in the move buffer will be executed at the slew
speed they were loaded with. The
FEEDRATE keyword is useful in making Mint programs easier to
read. When in ‘feedrate mode’, the
FEEDRATE keyword is used to set slew speed. When in ‘speed
mode’ the
SPEED keyword is used to set slew speed.
Note that there is no difference between the SPEED and FEEDRATE keywords. Their
functionality is determined by the FEEDRATEMODE keyword.
Reading FEEDRATE returns the last value written. It does not return the slew speed of the currently
executing move. See
FEEDRATEMODE for further details.
FEEDRATE is applicable with the following move types:
•
MOVEA/MOVER
•
VECTORA/VECTORR
•
CIRCLEA/CIRCLER
•
OFFSET
•
HOLDTOANALOG
•
INCA/INCR
The slew speed, set with
FEEDRATE, may not be achieved if the move length is not sufficient to achieve
a trapezoidal profile.
If the
FEEDRATE is changed whilst in ‘speed mode’, it will affect all moves loaded into the buffer that
were in ‘speed mode’. The move in progress will ramp using the current
ACCEL and DECEL values to
the new
SPEED.
Slew speed can also be affected by the
FEEDRATEOVERRIDE keyword which allows the FEEDRATE
value to be modified by a percentage multiplier. See
FEEDRATEOVERRIDE for further details.
Example:
FEEDRATE = 20 : REM Set slew speed to 20 user units/second
SPEED = 20 : REM Set slew speed to 20 user units/second
Both of these are equivalent.
FEEDRATEMODE = 1 : REM Set ‘feedrate mode’
FEEDRATE = 50 : REM Slew speed of 50 uu/s
MOVER = 20
FEEDRATE = 30 : REM Set slew speed to 30 uu/s
MOVER = 20
GO
In the above example, the first move is executed with a slew speed of 50 user units per second and the
second move is executed with a slew speed of 30 user units per second. Changing the slew speed to 30
does not affect the first move because the
FEEDRATEMODE keyword was used to set the move buffer to
‘feedrate mode’.
See also:
ACCEL, DECEL, FEEDRATEMODE, FEEDRATEOVERRIDE, MAXSPEED, SPEED