FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 34

1. AXIS CONTROL

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This parameter sets a maximum allowable synchronization error for synchronization error
excessive alarm 2.
The setting for the slave axis is available.

8333

Synchronization error zero width for each axis

[Input type] Parameter input

[Data type] 2-word axis

[Unit of data] Detection unit

[Valid data range] 1 to 32767

When a synchronization error below the value set in this parameter is detected,
synchronization error compensation is not performed.
The setting for the slave axis is available.

8334

Synchronization error compensation gain for each axis

[Input type] Parameter input

[Data type] Word axis

[Valid data range] 1 to 1024

This parameter sets a synchronization error compensation gain.
Compensation pulses found by the following expression are output for the slave axis:
Compensation pulses = Synchronization error

(Ci/1024)

Ci: Compensation gain
The setting for the slave axis is available.

8335

Synchronization error zero width 2 for each axis

[Input type] Parameter input

[Data type] 2-word axis

[Unit of data] Detection unit

[Valid data range] 0 to 32767

This parameter sets synchronization error zero width 2 for synchronization error smooth
suppression.
The setting for the slave axis is available.

NOTE

Set a value less than the value set in parameter No. 8333.

8336

Synchronization error compensation gain 2 for each axis

[Input type] Parameter input

[Data type] Word axis

[Valid data range] 0 to 1024

This parameter sets synchronization error compensation gain 2 for synchronization error
smooth suppression.
The setting for the slave axis is available.

NOTE

Set a value less than the value set in parameter No. 8334.

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8337

M code for turning off synchronization in axis synchronous control

8338

M code for turning on synchronization in axis synchronous control

[Input type] Parameter input

[Data type] 2-word path

[Valid data range] 1 to 999999999

This parameter specifies an M code for switching between synchronous operation and
normal operation.
The M code set in this parameter is not buffered.

CAUTION

To switch between synchronous operation and normal operation,
specify the M code set in parameter No. 8337 or 8338.

1.6.14

Diagnosis Data

The synchronization error and compensation are displayed on the diagnostic screen.

3500

Synchronization error for each axis

[Unit of data] Detection unit

[Description] The difference between the positions of the master and slave axes (synchronization error)

is displayed.
It is displayed for the axis number of the slave axis.

3501

Synchronization error compensation for each axis

[Unit of data] Detection unit

[Description] The total number of compensation pulses output to the slave axis (synchronization error

compensation) is displayed. This number is displayed for the axis number of the slave
axis.

1.6.15

Alarm and Message

Number

Message

Description

PS0213

ILLEGAL COMMAND IN
SYNCHRO-MODE

In axis synchronous control, the following errors occurred during
the synchronous operation.
1) The program issued the move command to the slave axis.
2) The manual operation (jog feed or incremental feed) is

performed to the slave axis.

3) The program issued the automatic reference position return

command without specifying the manual reference position
return after the power was turned on.

PS5379

WRITE PROTECTED TO SLAVE
AXIS

It is not possible to directly set the parameters for the slave axis
under axis synchronous control.

PS5580

CANNOT GET SYSTEM
VARIABLE

System variable (#180801 to #180850) cannot be read when
parameter No.8311 is incorrect value.
Confirm the setting of parameter No.8311.

DS0001

SYNC EXCESS ERROR (POS
DEV)

In axis synchronous control, the difference in the amount of
positional deviation between the master and slave axes
exceeded the parameter No. 8323 setting value.
This alarm occurs for the master or slave axis.

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Number

Message

Description

DS0002

SYNC EXCESS ERROR ALARM 1 In axis synchronous control, the difference in the amount of

synchronization between the master and slave axes exceeded
the parameter No. 8331 setting value.
This alarm occurs only for the slave axis.

DS0003

SYNCHRONIZE ADJUST MODE

The system is in the synchronize adjust mode.

SV0001

SYNC ALIGNMENT ERROR

In axis synchronous control, the amount of compensation for
synchronization exceeded the parameter No. 8325 setting value.
This alarm occurs for the master or slave axis.

SV0002

SYNC EXCESS ERROR ALARM 2 In axis synchronous control, the amount of synchronization error

exceeded the parameter No. 8332 setting value. When the
synchronization is not completed after power-up, the
determination is made by the parameter value No. 8332
multiplied by the parameter No. 8330 multiplier.
This alarm occurs only for a slave axis only.

SV0005

SYNC EXCESS ERROR (MCN)

In axis synchronous control, for synchronization, the difference
value of the machine coordinate between a master and slave
axes exceeded the parameter No. 8314 setting value.
This alarm occurs for a master or slave axis.

SV0420

SYNC TORQUE EXCESS

In axis synchronous control, for synchronization, the difference
value of torque between a master and slave axes exceeded the
parameter No. 2031 setting value.
This alarm occurs for a master axis.

1.6.16

Caution

CAUTION

1 When making a synchronization error check, ensure that the reference position

on the master axis and the reference position on the slave axis must be at the
same position.

2 In manual reference position return operation, the same operation is performed

along the master axis and slave axis until a deceleration operation starts. After a
deceleration operation starts, grid detection is performed for the master axis and
slave axis independently of each other.

3 Pitch error compensation and backlash compensation are performed for the

master axis and slave axis independently of each other.

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Note

NOTE

1 During axis synchronous control, a movement based on the reference position

return check (G27), automatic reference position return (G28), 2nd/3rd/4th
reference position return (G30), or machine coordinate system selection (G53)
command is made as described below according to the setting of bit 2 (SRF) of
parameter No. 8305.
<1> When SRF = 0, the same movement as made along the master axis is

made along the slave axis.

<2> When SRF = 1, a movement is made along the slave axis to the specified

position independently of a movement made along the master axis to the
specified position.

2 A command not involving a movement along an axis such as the workpiece

coordinate system setting command (G92) and local coordinate system setting
command (G52) is set with the master axis according to the master axis
programming.

3 During synchronous operation, the axis-by-axis signals such as for external

deceleration, interlock, and machine lock are enabled for the master axis only.
During synchronous operation, those signals for the slave axis are ignored.

4 When switching the synchronization state in a program, be sure to specify M

codes (parameters Nos. 8337 and 8338) for turning synchronization on and off.
By switching between the input signals SYNC <Gn138> and SYNCJ <Gn140>
from the PMC with the M codes, the synchronization state can be switched in the
program.

5 When controlled axis detach is performed, the synchronization state is cancelled.

When performing controlled axis detach, perform detach for the master axis and
slave axis at the same time.

6 If a programmed command is specified for the slave axis during synchronous

operation, an alarm PS0213, “ILLEGAL COMMAND IN SYN-CHRO-MODE” is
issued.

A programmed command can be specified for the slave axis when switching
between synchronous operation and normal operation is set to 0 (with bit 5
(SCAx) of parameter No. 8304 set to 0) and the signal SYNC/SYNCJ select
normal operation.

7 Axis synchronous control and PMC axis control cannot be used at the same

time.

8 When bit 4 (SYPx) of parameter No. 8303 is changed from 0 to 1 to use

automatic slave axis parameter setting, those slave axis parameters that have
already been set are not automatically set. Automatic slave axis parameter
setting is enabled after parameter No. 8311 and bit 4 (SYPx) of parameter No.
8303 are set.

9 If inputting a parameter file after enabling automatic slave axis parameter

setting, set parameter No. 8311 and bit 4 (SYPx) of parameter No. 8303 for both
the CNC and the parameter file before inputting it.

10 If the manual handle interrupt and the tool retract and recover is performed on

the axes of axis synchronous control, set “1” to signal SYNCJ.

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NOTE

11 When the machine lock is effective, the coordinate of master axis is as follows.

- The absolute and relative coordinate are updated.
- The machine coordinate is not updated.

And, the absolute, relative and machine coordinate of slave axis are not

updated.

Reference item

Manual name

Item name

OPERATOR’S MANUAL (B-64694EN)

Axis synchronous control

1.7

TANDEM CONTROL

Overview

If a single motor cannot produce sufficient torque to move a large table, for example, this function allows
two motors to be used. By means of this function, two motors can be used to perform movement along a
single axis.
Positioning is carried out only for the master axis. The slave axis is used only to produce a torque. By
means of this function, double the amount of torque can be obtained.

Fig. 1.7 (a)

The CNC generally processes the two axes of tandem control as a single axis. In the management of servo
parameters and the monitoring of servo alarms, however, the two axes are handled individually.

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Specified
pulse

Position

loop

Velocity

loop

Built-in
detector

Separate
detector

Scale

Average?

Reverse?

Bit 1 (OPT) of
parameter No. 1815

Parameter
VFA(No.2008#2)

Parameter
No. 2022

Parameter No. 2087
Preload (L)

Speed FB

Current

loop

Rotor
position

Servo

amplifier

Power
line

Master

axis

Speed FB

Power
line

Parameter No. 2087
Preload (M)

Slave axis

PWM

Servo

amplifier

Current

loop

Rotor
position

PWM

Reverse?

Parameter
No. 2022

Pulsecoder

Fig. 1.7 (b) Block Diagram of Tandem Control

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Explanation

Axis configuration in tandem control

To specify the axis configuration in tandem control, follow the procedure below:
(1) Tandem control can be performed for up to sixteen pairs of axes.

It can be performed for up to twelve pairs of axes for each path.

(2) In terms of controlled axes, the pair of axes is handled as two separate axes. For a programmed

command or manual feed, the pair of axes is handled as a single axis.

(3) The pair of axes is handled as two separate axes in the management of servo parameters and the

monitoring of servo alarms.

(4) Assign two consecutive numbers, that is one odd and one even number, to the master and slave axes

as their servo axis numbers (parameter No. 1023). Assign the smaller number to the master axis.
(Example)

If the servo axis number of the master axis (parameter No. 1023) is set to 1, specify servo axis
number 2 for the corresponding slave axis. If the servo axis number of the master axis is set to
3, specify servo axis number 4 for the corresponding slave axis.

In terms of controlled axis order, it is necessary to set master axis ahead of slave axis.

(5) The master and slave axes may have the same name or different names.
(6) A subscript can be attached to an axis name like X1, X2, XM, and XS. If the same axis name is used

for multiple axes, and a unique subscript is assigned to each of those axes, the axes can be
distinguished from each other on the screen display, or which of those axes issued an alarm can be
identified.

Set a subscript in parameter No. 3131.

(7) The slave axis is handled as a controlled axis. Set bit 0 (NDPx) of parameter No. 3115 to 1 to

suppress the position display.

The following sample axis configuration is for a machine with five axes X, Y, Z, A, and B. The
X-axis and Y-axis are the master axes of tandem control.

Number of controlled axes = Seven

Table 1.7 (a)

Axis

number

Displayed

axis name

Axis name

(No.1020)

Subscript

(No.3131)

Servo axis

number

(No.1023)

Tandem axis

(No.1817#6)

Master axis of tandem control

Slave axis of tandem control

Master axis of tandem control

Slave axis of tandem control

(8) The master and slave axes must be included in the same path.
(9) Set an absolute position detector only on the master axis. If it is set on the slave axis, alarm SV0006

"ILLEGAL TANDEM AXIS" is issued.

Preload function

By adding an offset to the torque controlled by the position (velocity) feedback device, the function can
apply opposite torques to the master and slave axes so that equal and opposite movements are performed
for both axes. This function can reduce the effect of backlash on the master and slave axes caused by the
tandem connection of the two motors via a gear. This function, however, cannot reduce backlash between
the ball screw and table or other backlash inherent to the machine.
If a preload of X is set for the master axis and -X for the slave axis, the opposing preload torques are
continuously applied to the two axes, even at rest, as shown below (Fig. 1.7 (c)):

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Master axis

Slave axis

-X

Fig. 1.7 (c)

CAUTION

1 Specify as low a preload as possible. Avoid specifying a preload higher than the

rated torque. Too high a preload will trigger an overload alarm because the
specified torques continue to be applied, even at rest. A preload that is only
slightly higher than the frictional force is recommended. Thus, the recommended
preload may be about one-third of the rated torque.

2 If the motors rotate in opposite directions (different signs are specified in

parameter No. 2022), specify the preload values with the same sign.

Velocity feedback average function

As shown in the block diagram of tandem control, the motor of the slave axis is not subject to velocity
control. A machine with a large amount of backlash may become unstable if the motor of the slave axis
vibrates as a result of backlash in the gear. This can be overcome by applying velocity control to the slave
axis also. This velocity feedback average function is enabled when bit 2 of parameter No. 2008 is set to 1.

Improved stability of a closed-loop system

The following two functions can increase the stability and position gain of a closed-loop system having a
linear scale:
-

Dual position feedback function

Machine velocity feedback function

For details of these functions, refer to "FANUC AC SERVO MOTOR

series, LINEAR MOTOR

S series, SYNCHRONOUS BUILT-IN SERVO MOTOR D

S series PARAMETER MANUAL

(B-65270EN)".

Notes on stability of tandem control

An important factor affecting stability in tandem control is the capability of back feed. Back feed is to
cause movement along either the master or slave axis from the other axis, via the transmission mechanism
connecting the two axes. A machine without this capability may be inclined to become unstable and
require adjustments.

Connection of axis signals

The DI/DO signals, generally connected to each axis, must be connected only to the master axis of two
axes of tandem control. The signals need not be connected to the slave axis. The following signals,
however, may have to be connected depending on the application.
i)

Controlled axis detach signals DTCH1 to DTCH8<Gn124> and servo off signals SVF1 to
SVF8<Gn126>
Connect these signals so that the master and slave axis signals are simultaneously input.

ii)

Overtravel signals *+L1 to *+L8<Gn114>, *-L1 to *-L8<Gn116>
Connect the signal so that 1 is always output as the overtravel signal for the slave axis.

If the slave axis stroke limit must also be detected, connect the signals so that the signal detected on the
slave axis is sent to the overtravel signal of the master axis.

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