Difference between revisions of "MC-Basic:axis.FOLLOWINGMODE"
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* user-following-BIT3 (PCMD = PCMD<sub>0 </sub>) freezing the PCMD value (not changing) (fmode = -3) with drive's PFB exit | * user-following-BIT3 (PCMD = PCMD<sub>0 </sub>) freezing the PCMD value (not changing) (fmode = -3) with drive's PFB exit | ||
| + | |||
| + | For '''BIT3''' see: [[AXY:SERCOS_Operation_Modes#Table_44_-_Structure_of_drive_operation_modes | SERCOS drive status word]] | ||
Revision as of 09:11, 23 November 2011
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 |
| Querying the fmode property returns 0 for regular working mode and 1 for all other types of following modes! |
 | NOTE |
| 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