FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 94

4. REFERENCE POSITION ESTABLISHMENT

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Installation conditions for deceleration limit switch

When installing the deceleration limit switch for manual reference position return, ensure that following
conditions are satisfied:

*DEC1

Grid

Feedrate

Rapid traverse
rate (VR)

Deceleration limit
operation position

FL rate (VL)

. . . . . . . . .

LDA

LDW

Reference position

Deceleration
limit release
position

(1) LDW : Deceleration dog width [mm, inch]

LDW

VL TS







1000

VR  : Rapid traverse [mm/min, inch/min]
TR  : Rapid traverse time constant [ms]
TS  : Servo time constant [ms]
VL  : FL speed for reference position return [mm/min, inch/min]

(2) LDA:

Distance between deceleration limit switch released position and reference position

LDA = Move amount of 1/2 revolution of motor

Since the above conditions do not include the limit switch operation variations, this point must also be
considered at installation.

Servo position error and one-rotation signal

To perform the first manual reference position return after power on, the tool must be fed in manual
reference position return mode, in the reference position return direction at a speed so that the servo
position error exceeds the value set in parameter No. 1836. At that time, the tool must cross the grid line
corresponding to a one-rotation signal from the position detector.
By the above operation, an electrical grid is established based on one-rotation signals from the position
detector.

The servo position error is calculated from the following formula:

1000

amount

error

position

Servo

F : Feedrate [mm/min]
G : Servo loop gain [s-1]
U : Detection unit [

(Example)

When the tool is fed at a feedrate F of 6000 mm/min with a servo loop gain G of 30 [s

-1

] and a

detection unit U of 1 [

m], the servo position error is calculated as follows:

1000

6000

error

position

Servo

= 3333

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By reversing the formula above, the following formula gives the feedrate F needed to obtain a servo
position error of 128, when the servo loop gain G is 30 [s

-1

] and the detection unit U is 1 [

m]:

128

1000

= 230 [mm/min]

Therefore, when the servo loop gain is 30 [s

-1

], the detection unit is 1 [

m], and parameter No. 1836

is set to 128, the tool must be fed in the reference position return direction at a speed of at least 230
mm/min before completing manual reference position return.

When the one-rotation signal from the position detector is seized at the time of manual reference
position return, bit 6 (PCR) of diagnosis data No. 201 is set to 1, and a grid for manual reference
position return is established, enabling manual reference position return.

NOTE

This bit has no effect until the operation of the manual reference position return
mode starts.

Adjusting the reference position

There are the following reference position adjustment methods: Method by grid shift and method by
reference position shift.
To shift the reference position within the distance to the first grid point, select the method by grid shift
and set bit 4 (SFDx) of parameter No. 1008 to 0.
To shift the reference position beyond the distance to the first grid point, select the method by reference
position shift and set bit 4 (SFDx) of parameter No. 1008 to 1.
Either of the methods for adjusting the reference position is available.

Adjusting the reference position by grid shift

With the method for shifting the reference position by grid shift, the grid position can be shifted by the
distance set in parameter No. 1850.
The distance by which the grid is to be shifted must not exceed the reference counter capacity (parameter
No. 1821).
The distance between the tool and the first grid point after the tool leaves the limit switch for deceleration
is indicated in diagnosis data No. 302. Furthermore, it is automatically stored in parameter No. 1844.

Adjusting the reference position by reference position shift

With the method for shifting the reference position by reference position shift, the distance by which the
reference position is to be shifted can be set in a parameter to shift it without moving the deceleration
dog.

This function is enabled by setting bit 4 (SFDx) of parameter No. 1008.
The distance by which the reference position is to be shifted, shown in the figure below, can be set in
parameter No. 1850 to shift the reference position.
The distance L

DEC

for the axis along which reference position return is performed is automatically stored

in parameter No. 1844. The distance L

DEC

is indicated in diagnosis data No. 302.

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Deceleration dog

Reference position

Grid point

Reference position return direction

DEC

Distance from the end of the deceleration dog to the first grid point after that when the distance by
which the reference position is to be shifted is 0 (parameter No. 1844)

SFT

: Distance by which the reference position is to be shifted (parameter No. 1850)

SFT

Set the following parameter. After setting, turn the power off, then on again.
Set bit 4 (SFDx) of parameter No. 1008 to 1.
The distance from the end of the deceleration dog to the first grid point after that (LDEC (parameter
No. 1844)) is 0 when the distance by which the reference position is to be shifted is 0.
Set the distance by which the reference position is to be shifted (parameter No. 1850) to 0.

Perform reference position return. The machine stops at the first grid point after leaving the
deceleration dog.
The distance LDEC is automatically set in parameter No. 1844. The distance LDEC is indicated in
diagnosis data No. 302.

Deceleration dog

Reference position

Grid point

Reference position return direction

Stop point

DEC

SFT

Obtain the distance from the stop position to the reference position (distance by which the reference
position is to be shifted (LSFT)) and set it in parameter No. 1850.
Then, turn the power off.
Adjusting the reference position is now completed.

The machine stops at the reference position when reference position return is performed after that.

Deceleration dog

Grid point

Reference position return direction

Stop point

DEC

SFT

Reference position

CAUTION

1 Reference position shift is effective only for reference position return using grid

points.

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CAUTION

2 Install a deceleration dog so that the distance between the end of the

deceleration dog and the first grid point after that is at least 1/2 of the interval
between grid points.

3 When the distance by which the reference position is to be shifted is 0, the

distance between the end of the deceleration dog and the first grid point after
that (LDEC (parameter No. 1844)) is automatically set. Do not change the
automatically set value.

4 This function cannot be used together with reference position setting without

dog.

5 This function cannot be used together with the grid compensation function in

feed axis synchronous control.

6 This function cannot be used in case of using method of specifying the reference

counter capacity with a fraction (Parameter (No.2179))

Manual reference position return for a rotation axis about which the tool can
rotate one or more turns

For a linear axis, when manual reference position return is performed, the relevant reference position
return deceleration signal (*DEC1, *DEC2, *DEC3, ...) is set to 1. At this time, if an electric grid based
on one-rotation signals from the position detector is not established, an alarm (PS0090) is issued.

For a rotation axis about which the tool can rotate one or more turns (type A) [bit 0 (ROTx) of parameter
No. 1006 is set to 1 and bit 1 (ROSx) of parameter No. 1006 is set to 0], bit 1 (RTLx) of parameter No.
1007 can be set to 1 to specify that the alarm is not issued in this case.
With this setting, manual reference position return may be started with the relevant reference position
return deceleration signal (*DEC1, *DEC2, *DEC3, ...) on the machine set to on. In this case, the
machine moves not at the reference position return FL feedrate, but at the feedrate set in the relevant
parameter.
Since the tool can rotate one or more turns about the rotation axis, it rotates one more turn. When the
relevant reference position return deceleration signal (*DEC1, *DEC2, *DEC3, ...) on the machine is
turned on, manual reference position return is performed in the same sequence as for normal manual
reference position return.

NOTE

When bit 1 (RTLx) of parameter No. 1007 is set to 0, the relevant reference
position return deceleration signal (*DEC1, *DEC2, *DEC3, ...) may be set to 1
before a grid is established. In this case, an alarm (PS0090) is issued.

For a rotation axis about which the tool can rotate up to one turn (type B) [bits 0 (ROTx) and 1 (ROSx) of
parameter No. 1006 are set to 1], when the relevant reference position return deceleration signal (*DEC1,
*DEC2, *DEC3, ...) is set to 1, a grid may not be established. In this case, an alarm (PS0090) is issued in
the same manner as for a linear axis.

High-speed manual reference position return after the reference position is
established

After the reference position is established, the tool can be positioned at the feedrate set in the relevant
parameter independently of the deceleration dog for manual reference position return. This operation is
enabled by setting bit 7 (SJZ) of parameter No. 0002 and bit 3 (HJZx) of parameter No. 1005.
This operation is called high-speed manual reference position return.

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After the reference position is established, setting a feed axis and direction selection signal to 1 in the
manual reference position return mode positions the tool at the reference position. This positioning is
performed irrespective of the direction specified by the feed axis and direction selection signal. After the
completion of the positioning, the relevant reference position return end signal is set to 1.

CAUTION

For high-speed manual reference position return, a feed axis and direction
selection signal may be selected in the manual reference position return mode. In
this case, the tool may be positioned at the reference position irrespective of the
direction specified by the feed axis and direction selection signal, depending on
the current position.

If the reference position is lost, manual reference position return using a deceleration dog is performed.

Coordinate system presetting during high-speed manual reference position
return

During high-speed manual reference position return, it is possible to select whether to preset the
coordinate system under the conditions below.
The following applies if the workpiece coordinate system is absent and automatic coordinate system
setting bit 0 (ZPR) of parameter No. 1201 is 0:
Bit 1 (HZP) of parameter No. 1206 = 0: The coordinate system is preset.
Bit 1 (HZP) of parameter No. 1206 = 1: The coordinate system is not preset.

Signal

Manual reference position return selection signal ZRN<Gn043.7>

[Classification] Input signal

[Function] This signal selects manual reference position return.

Manual reference position return is a kind of jog feed. Therefore, to select manual
reference position return, it is required that the jog mode be selected and that the manual
reference position return selection signal be set to 1.

[Operation] When the manual reference position return selection signal is set to 1, the control unit

performs as described below.
-

If jog feed mode is not selected, the control unit ignores the manual reference
position return selection signal.

If jog mode is selected, manual reference position return is enabled. In this case, the
manual reference position return selection check signal MREF turns to 1.

NOTE

If the ZRN status changes state during jog feed, the feedrate is
decelerated to 0. Then, to restart reference position return or jog
feed, turn feed axis and direction selection signal to 0 then set it to
1.

Manual reference position return selection check signal MREF<Fn004.5>

[Classification] Output signal

[Function] This signal indicates that manual reference position return has been selected.

[Output cond.] This signal turns to 1 when:

Manual reference position return has been selected.

The signal turns to 0 when:
-

The selection of manual reference position return has terminated.

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Feed axis and direction selection signal

For details about this signal, see "Feed Axis and Direction Selection Signal". Only notes on use of
reference position return are given, here.

NOTE

1 The direction of reference position return is set for each axis by bit

5 (ZMI) of parameter No. 1006. If the tool is fed opposite to the
preset direction in manual reference position return, while the
deceleration signal is 0, the tool feeds until the signal returns to 1.
The reference position return is then performed automatically in the
predetermined direction.

Rapid traverse
rate

FL rate

. . . . . . . . . . . . . . . . . . . .

JOG mode or
TEACH IN JOG mode

ZRN

-J1

*DEC1

Grid

ZP1

ZRF1

Rapid
traverse
rate

Feedrate

NOTE

2 When reference position return is selected, an axis who has

already completed referencing movement along that axis is
disabled while the reference position return selection signal (ZRN)
is 1. To perform movement again, ZRN must be set 0, and the feed
axis and direction selection signal must be reset to 0 and then
returned to 1 again.

Reference position return deceleration signals *DEC1 to *DEC8<X009>,

*DEC1

to *DEC8

<X007>,

*DEC1

to *DEC8

<X010>

[Classification] Input signal

[Function] These signals decelerate the feedrate for manual reference position return to a low

feedrate (FL).
Deceleration signals are provided for each axis. The number appended to a deceleration
signal represents a controlled axis number.
*DECx
x : 1:Reference position return deceleration signal for the first axis

2:Reference position return deceleration signal for the second axis
3:Reference position return deceleration signal for the third axis
  :
  :

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[Operation] For a description of the control unit response to the deceleration signal, see the basic

procedure for manual reference position return.

The reference position return deceleration signals are assigned to path 1 to path 3.
For the axes that are assigned to path 1, *DEC1 to *DEC8 (X009) are valid.
For the axes that are assigned to path 2, *DEC1#2 to *DEC8#2 (X007) are valid.
For the axes that are assigned to path 3, *DEC1#3 to *DEC8#3 (X010) are valid.
The reference position return deceleration signals are not assigned to path 4.
(The X address and bit position for these signals for each path can be arbitrarily
determined by setting bit 2 (XSG) of parameter No. 3008 to 1.)

Bit 0 (GDC) of parameter No. 3006 can be set to 1 to use input signal Gn196.

NOTE

Bit 2 (XSG) of parameter No. 3008 can be set to specify whether to
fix the address of the reference position return deceleration signals
to X009 (path1), X007 (path2), X010 (path3) or use a desired X
address.

When bit 2 (XSG) of parameter No. 3008 is set to 1, the X address
and bit position for each reference position return deceleration
signal are determined according to the setting of parameters Nos.
3013 and 3014, for each path.

Bit 5 (DEC) of parameter No. 3003 can be set to set the logic for the deceleration signals
(*DEC1 to *DEC8).

Reference position return end signals ZP1 to ZP8<Fn094>

[Classification] Output signal

[Function] These signals report that the tool is at the reference position on a controlled axis.

These signals are provided for each axis. The number appended to a signal represents a
controlled axis number.
ZPx
x : 1 : Reference position return end signal for the first axis

2 : Reference position return end signal for the second axis
3 : Reference position return end signal for the third axis
:
:

[Output cond.] These signals are set to 1 when:

Manual reference position returns is completed, and the axis position is in the
in-position area.

Automatic reference position return (G28) is completed, and the axis position is in
the in-position area.

Reference position return check (G27) is completed, and the axis position is in the
in-position area.

These signals turn to 0when:
-

The tool has moved from the reference position.

An emergency stop is applied.

A servo alarm is raised.

Reference position establishment signal ZRF1 to ZRF8<Fn120>

[Classification] Output signal

[Function] Notify the system that the reference position has been established.

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A reference position establishment signal is provided for each axis. The number appended
to each signal indicates the number of the controlled axis.
ZRFx
x : 1 : 1st-axis reference position establishment signal

2 : 2nd-axis reference position establishment signal
3 : 3rd-axis reference position establishment signal
:
:

[Output cond.] The signals are set to 1 in the following case:

When the reference position is established after manual reference position return

When the reference position is established using the absolute-position detector at
initial power-on

When the reference position is lost, the signals are set to 0.

Signal address

X007

*DEC8

*DEC7

*DEC6

*DEC5

*DEC4

*DEC3

*DEC2

*DEC1

X009

*DEC8

*DEC7

*DEC6

*DEC5

*DEC4

*DEC3

*DEC2

*DEC1

X010

*DEC8

*DEC7

*DEC6

*DEC5

*DEC4

*DEC3

*DEC2

*DEC1

When the bit 0 (GDC) of parameter No. 3006 is set to 0.

Gn196

*DEC8

*DEC7

*DEC6

*DEC5

*DEC4

*DEC3

*DEC2

*DEC1

When the bit 0 (GDC) of parameter No. 3006 is set to 1.

Gn043

ZRN

Fn004

MREF

Fn094

ZP8

ZP7

ZP6

ZP5

ZP4

ZP3

ZP2

ZP1

Fn120

ZRF8

ZRF7

ZRF6

ZRF5

ZRF4

ZRF3

ZRF2

ZRF1

Parameter

0002

SJZ

[Input type] Setting input

[Data type] Bit

#7 SJZ

On an axis for which bit 3 (HJZx) of parameter No. 1005 is set:

If a reference position is not established yet, reference position return is performed
with deceleration dogs.

If a reference position is already established, reference position return is performed
at a parameter-set feedrate without using deceleration dogs.

Reference position return is performed with deceleration dogs at all times.

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