Installation guide

Mint™ v4 Advanced Programming Guide
80 MN1270 02.2002
FEEDRATEMODE/FRM
Purpose:
To control the use of slew speed and feedrate override.
Controllers Supported:
NextMove PCI NextMove PC NextMove BX MintDrive ServoNode 51
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Format:
FEEDRATEMODE[axes] = <expression> {,<expression> ...}
v = FEEDRATE[axis]
Dot Parameters:
Axis - Axis No.
Attributes:
Controller Read Write Command Multi-
Axis
Scaled Default Range
NextMove
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0
0 ≤ x ≤ 3
Description:
The
FEEDRATEMODE keyword controls the how the slew speed set with SPEED or FEEDRATE is
interpreted and also allows the affect of the
FEEDRATEOVERRIDE keyword to be enabled or disabled.
FEEDRATEMODE takes a bit pattern as follows:
Bit Meaning
0 Set to enable ‘feedrate mode’. ‘speed mode’ otherwise.
1 Set to enable FEEDRATEOVERRIDE. Disabled otherwise.
In ‘speed mode’, bit 0 not set, slew speed for positional moves is set with the
SPEED or FEEDRATE
keywords. Any change in slew speed takes immediate effect on moves already loaded into the move
buffer, the axis changing to the new slew speed at the current
ACCEL or DECEL rate.
Example:
FEEDRATEMODE = 0 : REM speed mode
SPEED = 30 : REM slew speed 30 uu/s
MOVER = 50 : REM relative move of 50 units
GO : REM start the move
PAUSE OFFSET < 25 : REM wait until half way
FEEDRATE = 10 : REM Change slew speed to 10 uu/s
In this example, the move is started and ramps to a slew speed of 30 user units per second. When there
is less than 25 units left to travel, the slew speed is changed to 10 user units per second. This will have
an immediate affect with the axis decelerating to the new slew speed.
In ‘feedrate mode’, bit 0 set, slew speed for positional moves is set with the
SPEED or FEEDRATE
keywords. The current slew speed is loaded with each positional move. When a move is executed from
the buffer, it uses the slew speed it was loaded with, regardless of the current slew speed.
The feedrate mode is stored as each move is loaded, therefore a move in the move buffer knows if it
was loaded in ‘speed’ or ‘feedrate’ mode. When loading moves with feedrate mode enabled, S-
ramping is automatically disabled. It is not possible to perform moves with S-ramping whilst in
feedrate mode.
Feedrate mode is useful for programming changes in slew speed across a number of moves. This is
useful in contouring applications where the slew speed of corners and complex shapes needs to be
slower than that of longer smoother shapes.
When contouring is turned on, a move will be performed at the specified
FEEDRATE or slower, if the
FEEDRATE of the next loaded move dictates that the axis needs to decelerate. If the next FEEDRATE is
higher than the current
FEEDRATE, then the axis will not accelerate until it passes into that next move.
I.E. Any acceleration or deceleration will always occur in the fastest of a pair of moves.