Deceleration Check - Mitsubishi Electric MELSEC iQ-R16MTCPU Programming Manual

Deceleration check

The deceleration check function reduces the impact on machinery when the feed speed of the control axis changes abruptly,
and can also prevent the rounding of corners when cutting corners by decelerating to a stop at the block joint, before
executing the next block.
No deceleration check
N010 G01 X100.
N011 G01 Y-50.
Because the transition to the
N011 block starts before the N010
command is entirely complete,
the rounding of corners occurs.
Conditions for execution of deceleration check
■Deceleration check during fast forward
For fast forward mode, when the movement for the block is complete a deceleration check is always performed before
executing the next block.
■Deceleration check during cutting feed
For cutting feed mode, when one of the following conditions is satisfied, a deceleration check is executed and movement for
the next block starts after the deceleration check is completed.
• When G61 (exact stop check mode) is selected.
• When G09 (exact stop check) is commanded in the same block.
• When there is an axis in the current block which moves in the reverse direction in the next block, and the conditions for the
combination of movement commands is satisfied. (Refer to deceleration check when movement changes to the reverse
direction for details. (Page 180 Deceleration check when movement changes to the reverse direction))
Deceleration check methods
There are three methods for deceleration check: Command deceleration check method, smoothing check method, and in-
position check method.
Set the deceleration check method in [Motion Control Parameter][G-code Control Parameter][G-code Control System
Parameter]"Control Setting""Deceleration Check".
■Command deceleration check method
After interpolation of a block is completed, and checking that the commanded deceleration is completed, the execution of the
next block starts. The following explains the transition from a block executing fast forward to the next block using examples.
The time required for deceleration check is the longest of the deceleration check times of each axis, which are determined by
the acceleration/deceleration modes and acceleration/deceleration time constants of each axis commanded at the same time.
Executing block
6 AUXILIARY AND APPLIED FUNCTIONS
178
6.3 Feed Function
Next block
Ts
Td
Deceleration check
N010 G09 G01 X100.
N011 G01 Y-50.
Because the N010 command
decelerates to a stop before
transition to the next block, the
edges are sharp.
Ts : Acceleration/deceleration time
Td : Deceleration check time
*1
Td=Ts+α(0 to 4ms )
*1: When the operation cycle is 1.777ms or more,
the deceleration check time is a maximum of
"operation cycle×4".