MC-Basic:axis.FOLLOWINGMODE

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This property puts the axis into following mode.

When the drive is in the disabled state, the position command (PCMD) is continually set equal to the position feedback. This state of an axis is called Following mode. When the drive is re-enabled, the PCMD sent will have the value of the last sample (when it was in following mode), so no jumps will occur. In situations in which the drive takes control of the motion of the motor (such as in drive-controlled homing), the axis must be put explicitly into Following mode. Otherwise, the softMC reports a position following error.

There are various types of Following modes:

• 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 (fmode=-2)
• User-following-BIT3 (PCMD = PCMD₀ ) freezing the PCMD value (not changing) (fmode = -3) with drive's PFB exit (fmode=-3)

For BIT3 see: SERCOS drive status word

	IMPORTANT
	User-following from type -2 and -3 are obsolete as SERCOS is not default protocol.

	IMPORTANT
	Querying the fmode property returns actual following mode, that is, 0 for normal operation and 1 for all other types of following modes! User input for following-mode can be query using UserFollowigMode property

	NOTE
	Be careful when setting Following mode to 2, as it closes a feedback loop around the position variable of the drive. It can lead to instability and motor run away!

	NOTE
	Not all modes are suppoted by EtherCAT and CANopen. Please refer to "Limitations"

	WARNING
	Disabling drive automatically activates hard-following mode from whatever mode the axis was previously in!

Short form

<axis>.Fmode

Syntax

<axis>.FollowingMode = <value>

Availability

• fmode = 0/1 – All versions
• fmode = 2 – Since Version 4.4.2
• fmode = -2/-3 – Since 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 SDO_0x208e 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 SDO_0x208e for new PCMD on exit.

• -3 – User-following by (PCMD = PCMD₀ )- drive status'-BIT3 control using AT cyclic telegram PFB 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).
• EtherCAT and CANopen: only modes 0 and 2 are supported

Examples

X_Axis.FollowingMode = ON

See Also

• ATTACH
• element.POSITIONCOMMAND
• axis.UserFollowingMode