Change Axis Positive / Negative Motion Direction

Owned by Perla Madrigal (Unlicensed)
Last updated: May 24, 2024
3 min read

Product: IPA, AriesCE, 9000, 9030, 9040, 9600,9630,9640

In some applications it may be desirable or necessary to change the controllers sense of positive and negative direction for an axis. The following methods will change both the commanded direction and encoder direction for an axis. These commands do not change the assignment of positive and negative home sensors, so these may need to be rewired.

Three cases below deal with different axis types: 1. DAC/servo, 2. EPL and Stepper, 3. Aries Controller

Case 1. ACR9xx0 series servo (DAC) axes, two settings must be changed in order to swap what the ACR sees as positive convention.
Check the values of the encoder multiplier and DAC Gain by issuing the MULT command and DAC# GAIN command respectively. Settings are also stored in the System Code.

P00>AXIS0 DRIVE OFF X
P00>ENC0 MULT
4
P00>DAC0 GAIN
3276.8

Change the signs of the encoder multiplier and DAC Gain
P00>ENC0 MULT-4
P00>DAC0 GAIN -3276.8
Issue ESAVE to retain these value after power cycle.

Notes: 

  • The Configuration Wizard will always set these values to DAC GAIN 3276.8 and MULT 4. If the direction needs to change, the modified commands must be issued after a configuration download.  Consider adding to the Defines file or a PBOOT program that initializes other application settings.   

  • The Servo Tuner and Jog/Home dialogs included in the Configuration Wizard will resend the default settings. Avoid these dialogs after making direction changes. If needed, use the Servo Tuner and Jog/Teach panel locate under Tools in the ACR-View project workspace.

  •  With some drive/motor combinations, the command direction (DAC GAIN) and encoder direction (MULT) may need to be different. For Example DAC0 GAIN 3276.8 and ENC0 MULT-4. Use caution when making this type of change as it could result in a runaway condition.

Case 2: Stepper axes (without encoder) or EthernetPowerlink axes (for ACR9630/9640 or ACR9030/9040) set the Invert Motion Direct Flags, e.g. bit 8455 (for axis0). Requires ESAVE command to retain setting after power cycle.

Case 3: IPA or Aries Controller (AR-xxCE), set the Invert Motion Direction Flag bit 8455. Requires FLASH SAVE or FLASH IMAGE command to retain setting after power cycle.  

Notes: 

  • The Invert Motion Direction Flag is not part of the configuration wizard but could be added to the Defines or a PBOOT program that initializes application settings.   

  •  SET or CLR of the Invert Motion flag is only allowed while the Drive is off/disabled for the axis. NOT VALID WHILE DRIVE ENABLED error will result if SET or CLR is issued while the drive is enabled. If the error occurs in a running program, that program will HALT automatically. 

  •   For a DAC axis the Invert Motion Direction flag will invert the sign of both MULT and DAC GAIN. Each time you SET this bit, these values are multiplied by -1. Recommend instead setting DAC GAIN and MULT explicitly somewhere in code to the needed settings as described in case #1

  • In an IEC61131 PLC program use the MC_WRITEBOOLParameter Function block where ParmeterNumber=103 and VALUE=TRUE to set the InvertMotion Flags. Make sure to only call this block while MC_Power is not enabled.

     

     

invertmotion_3585-20240521-000857.jpg

 

 

 Case 4: Stepper with encoder: See attached code samples:  

SetPositive.txt

SetNegative.txt

 

 

 

 ACR7000: In Parker Motion Manager Configuration Wizard, direction can be inverted via a check box selection.