MC-Basic:axis.FOLLOWINGMODE

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When the drive is disabled, the position command (PCMD) is continually set equal to the position feedback. In situations where the drive takes control over the motion of the motor (such as in drive-controlled homing), the axis must be explicitly put into FOLLOWINGMODE. Otherwise, the MC reports a position following error.

This property put the axis in FOLLOWINGMODE. There are different modes of the follwing-mode:

  • hard-following (PCMD = PFB) automatically entered by the system when drive is disabled
  • user-following (PCMD = PCMD0 ) freezing the PCMD value (not changing) (fmode = 1)
  • soft-following (PCMD = PFB) same as hard-follwing (fmode=2)
  • user-following-BIT3 (PCMD = PCMD0 ) freezing the PCMD value (not changing) (fmode = -2) with drive's PCMD exit
  • user-following-BIT3 (PCMD = PCMD0 ) freezing the PCMD value (not changing) (fmode = -3) with drive's PFB exit


For BIT3 see: SERCOS drive status word


IMPORTANT.svgIMPORTANT
Querying the fmode property returns 0 for regular working mode and 1 for all other types of following modes!
NOTE-Info.svgNOTE
Be careful when setting following mode to 2, as it closes a loop around the position variable of the drive it can lead to instability - run away!

Short form

<axis>.Fmode

Syntax

<axis>.FollowingMode = <value>

Availability

  • fmode = 0/1 - All versions
  • fmode = 2 From 4.4.2
  • fmode = -2/-3 From 4.9.0

Type

Long

Range

  • 0 –( Default ) When axis is enabled and the Position Error is monitored
  • 1 -When axis is disabled  or can be set by the user.  It freezes the PositionCommand.. And PositionCommand will update on the end (when user enters Fmode=0) by reading the IDN47 from the drive. (This can take some time as it is done through SERCOS service channel).
  • 2 -soft-following-mode, keeps PositionCommand equal to PositionFeedback .
  • -2 -user-following by (PCMD = PCMD0 )- drive status'-BIT3 control using AT cyclic telegram's IDN47 for new PCMD on exit
  • -3 -user-following by (PCMD = PCMD0 )- drive status'-BIT3 control using AT cyclic telegram'sPFB for new PCMD on exit

Default

0

Scope

Configuration, Task or Terminal

Limitations

To set the value within a task, the axis must be attached to that task (using the ATTACH command).

Examples

X_Axis.FollowingMode = ON

See Also

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