Elmo HARmonica, HARSFEN0602 software manual 176, Homing Programming, Homing the auxiliary encoder

HARSFEN0602ElmoHARmonicaSoftwareManual PRELIMINARYDRAFT

Absolute position control in the single-feedback position-control mode.

•Relative work in the single-feedback position-control mode. For example, an axis in a machine

may be homed by sensor of the edge of the product the machine works on. The position referencing of the axis becomes relative to the product.

Homing of the main position counter (PY) typically serves for:

Absolute position control in the dual-feedback position-control mode.

Relative work in the dual-feedback position-control mode.

•In the single-feedback position-control mode: Fixing the origin for the external position command-see Section 12.2.1.

In the homing process, a trap is set for the event of reaching a desired position. The motor travels until an expected event occurs. The event marks that the motor is now in a known absolute position. This known position, if set to the position counter at the time of the event, makes the position reading of the Amplifier absolute.

The looked-for event may be one of the limit switches (RLS or FLS), the home switch, the encoder index or the digital inputs. The capture accuracy depends, however, much in the homing event selection. If a HOME or an INDEX signal is selected as the captured event, then the captured position will not miss. If another digital input is selected, the sensing delay for the switch is d=(0.004*TS+IF[N]) msec, and VX*d/1000 counts may be missed.

Example

Suppose:

Parameter			Symbol		Value
Torque controller sampling time,			TS		50
usec
Input filter width for digital input			IF[1]		2
#1, msec
Motor main speed, count/sec			VX		20000
When homing on Digital Input #1, we expect to miss
miss =	VX ⋅ (0.004 ⋅ TS + IF[1])			20000 ⋅ (0.004 ⋅ 50 + 2)
		=				= 44count
1000		1000

To capture an event, the event must be first defined by a proper IL[N] setting. For example, if no digital input is associated to the FLS function, a homing process on the FLS will never terminate. Moreover, it is legal to un-define the FLS function while a home search on the FLS is on. The home search will not succeed until FLS is re- defined.

13.5.2 Homing Programming

The HM[] parameters control The main encoder homing process.

HM[3] defines the trigger event – immediately, or the change of some digital input. HM[4] is what to do after the event, in addition to position registration. You can command the amplifier to stop immediately, or to flag a digital output.

HM[5] defines if and how to update the main encoder counter – do nothing, set a

•new value, or shift by a known amount.

HM[1]=1 arms the homing process (sets the trap for the homing event).

Refer the HM[] command in the Command Reference Manual for details.

13.5.3Homing the auxiliary encoder

The HY homing function gives an additional homing and capturing function.

HY is very similar to HM, except that HY refers the auxiliary Home switch and Index signals instead of the main Home switch and Index, and that HY can update the value

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