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TB137 Rev2 Setting Direction Reversal
Overview
This document describes the procedure used to correctly set Direction Reversal for a knee or bed mill This document assumes that
the motors pulleys and belts have been correctly installed on the machine Setting the motor for direction reversal is simple but it does
complicate the limit switch settings somewhat
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When Direction reversal is Needed
Direction reversal should only be a factor during the initial setup of a unit or if the configuration has to be redone from initial default
Example Customer has a hard drive crash and no backup of configuration The symptoms of a motor that needs direction reversal
would be that the motor moves in the opposite direction of commanded travel This motion is normal smooth motion and the DRO
readout reads as if the motion was correct This is caused by the way that the motor is coupled to the ball screw Both of the following
diagrams show rotation for an axis moving in the same direction But in the top diagram the motor is facing the ball screw and in the
bottom diagram the motor is facing the same direction as the ball screw So even though the ball screw is turning the same way in both
diagrams the motor is not
Starting at the main screen Press F1 Setup
F3 Config
enter the password default is 137
F2 Machine
and F2 Motor
Use the
arrow keys to select the proper motor under the column Dir Rev Use the space bar to toggle Dir Rev from N to Y Press F10 Save
to
save changes The motor should now go in the proper direction when commanded  Centoid DC drives are hardwired to look at the limit
switches one way and one way only  So for SERVO1 QUADDRV1 SERVO3IO DC3IO DC3IOB and ALLIN1DC drives the limits
need to be changed to statisfy the drive
Limit Switch/Limit Input Adjustments
Starting at the main screen Press F1 Setup
F3 Config
enter the password default is 137
F2 Machine
and F2 Motor
The
Limit and Home Switch inputs will need to be flipped for axes with direction reversal turned on  For example the X axis typically has
the negative limit and home switch set to 1 and the positive set to 2 With direction reversal turned on these will be flipped That
means that the positive limit and home switch will become 1 and the negative will be 2 Â Once all required inputs are changed press
F10 Save
to save the configuration changes
Â
Before Direction Reversal Â
After Direction Reversal
Axis Label Limit Home Dir Rev Â
Axis Label Limit Home Dir Rev
Â
+ + Â
> Â
+ _ + Â
X 1 2 1 2 N Â
X 2 1 2 1 Y
Â
Now that the software side is done there is one last step You will need to switch the plus and minus limit switch wires on the PLC for
the direction reversal to be complete and operate correctly
If the limits are correct you will be able to trip a limit the correct limit tripped message will appear on the screen and you will be able to
slow jog off of the limit while it is tripped
If you get the correct message when a limit is tripped but when you try to jog you get Full Power Without Motion the limit switch is
connected to the wrong input of the PLC and servo drive The message is correct because the PLC is being told to look for the limit
switch on the wrong input To correct this swap the limit switch to the other input for that axis and swap the numbers for the Limits and
Home Switch in the setup screen
 If you get the wrong message when a limit is tripped and when you try to jog the axis will move a slight amount then the limit switch is
connected to the correct input but the PLC is being told to look for the limit switch on the wrong input To correct this swap the
numbers for the Limits and Home Switch in the setup screen
 If you get the wrong message when a limit is tripped and when you try to jog you get Full Power Without Motion the limit switch is
connected to the wrong limit of the PLC and servo drive To correct this swap the limit switch to the other input for that axis
Document History
Rev2 Created on 2011 08 24
by #240
Rev1 Created on 2011 08 24
by #240