Content Preview
TB289 REV1 Γ’ Software Travel Limits
Without software travel limits the machine can go maximum speed until a limit is tripped as shown in Figure 1
Often times there is not enough time to decelerate the axis after the limit switch is tripped causing the machine to crash into
the hard stop This collision may cause serious damage to both the mechanical and electrical system
Setting software travel limits will automatically decelerate the axis right before it reaches the limit switch preventing
possible damage to the machine as shown in Figure 2 Additionally the CNC11 software will throw an error and stop the
machine if a G code requests the machine to move past the software travel limit
1 Prerequisites Before starting machine revs per inch / mm DRO needs to be calibrated correctly the limit switches
need to be functioning and the maximum feed rate and acceleration should be correctly set up Restart the machine
and home it before continuing with this procedure
2 Make sure your looking at the machine position and not the part position From any menu press the Γ’ alt Γ’ key and Γ’ D Γ’
key simultaneously until Γ’ machine Γ’ is displayed in the top left corner of the DRO as shown in Figure 3
3 Put the machine into Γ’ Slow jog Γ’ mode and turn the feed rate down Slowly moves the axis away from home toward the
limit switch on the opposite end of the axis until the limit switch trips The status screen will display message such as
Γ’ 407 ## limit #50004 tripped Γ’
4 Put the jog panel into incremental mode Slowly increment to away from the limit switch until the limit switch is cleared
The status screen will display a message such as Γ’ 340 ## limit #5003 cleared Γ’
5 From the main menu press F3 MDI and issue a command to move another 0 1 inches 2 5 millimeters away from the
limit switch This DRO position will be our software travel limit
6 From the main menu press F1 Γ’ Setup Γ’ F3 config The password is 137 Press F2 Mach Γ’ F1 Jog In the jog
parameters menu Enter the position for the software travel limit into the appropriate Γ’ Travel Γ’ or Γ’ Travel + Γ’ box
7
1 NOTE When both the Travel limit and the Travel + limit are set to zero software travel limits are disabled As
soon as one of the two values change to a non zero value both limits are enabled This can be seen in figure 3
Since everything is referenced to machine position the side of each axis that you Γ’home toΓ’ should be left at zero
8 Repeat for each axis
192 168 0 199/public/tech/technical bulletins/TB Template with instructions odt 03/28/14 Page 1 of 2Figure 1
Machine without software travel limits Figure 2
Machine with software travel limits Limit
SwitchHard Stop
Maximum Feed Rate
Axis DecelerationSoftware travel limit reached
motors stopped
Limit Switch Tripped
Limit
SwitchHard Stop
Maximum Feed RateLimit switch tripped
motors commanded to stop Software automatically calculates
how to limit the feed rate to stop
at the software travel limit Axis Deceleration
TB289 REV1 Γ’ Software Travel Limits
9 Test by manually jogging each axis toward the limit switch Watch that the software automatically stops the axis at the
software travel limit before the limit switch is tripped Use the F3 Γ’ MDI menu to issue a G code that asks the software
to move just beyond the software travel limit if set up correctly the CNC11 status window will throw an error such as
Γ’ 907 # axis travel exceeded 325 Limit job canceled Γ’
Document History
Rev1 Created on 2014 09 25 by #369
192 168 0 199/public/tech/technical bulletins/TB Template with instructions odt 03/28/14 Page 2 of 2Figure 3
Setting Software Travel LimitsΓ’ altΓ’ + Γ’DΓ’ to toggle the
DRO mode to display the
machine cordinates
Set up software travel limits here