Influence on the look-ahead functionality (G115/G116/G117)

Syntax:

G115=..

General influencing of the look-ahead functionality

modal

G116 <axis_name>..
          
{ <axis_name>.. }

Influencing the calculation of block transition velocity

modal

G117

Resetting the look-ahead functionality

modal,
initial state

Overview of the functionality of the look-ahead function

Various single functions are implemented in the look-ahead function. They limit motion velocities to maximum values in order to always maintain the permissible axis velocities and axis accelerations.

The following single functions influence the velocity profile:

General case:

Normal mode with look-ahead

After program start all functionalities of the look-ahead function are switched on (G117). This ensures that the parameters specified in the channel parameter list P-CHAN-00071, e.g. maximum axis velocity and maximum axis acceleration, are always maintained.

Special case:

Switch off single functions of the look-ahead function by G115

Programing Example

prg_example

Influence the look-ahead functionality (G115/G116/G117)

Nnn G115 = 0

(Switch off the single functions (2),(3) and (4))

(of the look-ahead function)

The table below explains the possible combinations of the single functions.

Notice

notice

The corresponding selected or deselected functions always refer to all axes.

Overview of permissible identification numbers (ID) related to G115:

Single function


ID

 

(1)

 

(2)

 

(3)

 

(4)

0

*

 

 

 

2

*

 

 

*

4

*

*

 

 

6

*

*

 

*

8

*

 

*

 

10

*

 

*

*

12

*

*

*

 

14

*

*

*

*

*

Single function active

 

Single function not active

Programing Example

prg_example

Nnn G115 = 2   (Switch off single functions (2) and (3))

Nnn G115 = 12  (Switch off single functions and (4))

Nnn G115 = 14  (Switch off single functions after)

               (program start, cf. G117)

Special case:

Influence the look-ahead functionality with G116, G117

The G116 function switches off the calculation of the block transition velocity (single function (4)) for single programmable axes. No reduction in block transition velocity (path velocity) takes place because of "corners" in the path.

Notice

notice

In this case, the dynamic axis data (axis accelerations) are not normally maintained.

Programing Example

prg_example

N10 G116 X1 Y2              (No reduction in block transition)

                            (rate of different axis)

                            (rates of the axes X or Y)

N20 G01 G91 X100 Y-100 F1000    

N30 X-100    

In this example, block transition N20/N30 is traversed without any drop in set velocity. The command values change at the block transition in jumps according to the axis portions on the path.

Attention

attention

The coordinate value is only required for syntax reasons; otherwise it is irrelevant.

The G117 function switches all single function of the look-ahead function back to active (default setting after program start).

Programing Example

prg_example

Nnn G117

(Enable all single functions (1),(2),(3),(4))

(of the look-ahead function)