FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 124

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Even when a cycle start operation is performed while the reverse execution signal RVS is held 1,
operation is not performed, and the reverse execution end state is maintained. Forward reexecution (or
forward execution) is started by setting the reverse execution signal RVS to 0 then performing a cycle
start operation.

End of reverse execution
Reverse execution signal RVS = 0
Cycle start

Cycle start (start of forward execution)

Start of forward reexecution

Forward
Reverse
Forward reexecution

Start of reverse execution

Fig. 5.10 (g)

Forward reexecution

→

forward execution

After forward reexecution is performed up to the block at which reverse execution started, forward
execution starts automatically, and commands are read from the program again and executed. No
particular operation is required.

Cycle start (start of forward execution)

Start of forward reexecution

Forward
Reverse
Forward reexecution

Start of reverse execution

Restart of forward execution

Fig. 5.10 (h)

If reverse execution was performed after feed hold stop, forward reexecution ends when the feed hold
stop position is reached, then forward execution is performed. Also if single block operation was
performed, forward reexecution ends at the single block stop position.

Cycle start (start of forward execution)

Start of forward reexecution

Forward
Reverse
Forward reexecution

Feed hold stop
Reverse execution signal RVS = 1, cycle start

Start of reverse execution

Restart of forward execution

Fig. 5.10 (i)

Description

Reverse execution and forward execution

Usually in automatic operation, a program is executed in the programmed order. This is called forward
execution. This function allows a program executed by forward execution to be executed in the reverse
direction. This is called reverse execution. Reverse execution allows the tool to retrace the path along
which the tool has moved during forward execution.
Reverse execution of a program can be performed only for blocks that have been executed by forward
execution.
Furthermore, in single block operation, reverse execution can also be performed on a block-by-block
basis.

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Forward reexecution

Blocks that have been executed by reverse execution can be reexecuted in the forward direction up to the
block from which reverse execution started. This is called forward reexecution. Forward reexecution
allows the tool to retrace the same tool path as in forward execution until the position at which reverse
execution started is reached.
After the block from which reverse execution started is reached, the program is executed again in the
programmed order (forward execution).
Furthermore, in single block operation, forward reexecution can also be performed on a block-by-block
basis.

End of reverse execution

When a block to be executed is no longer present during reverse execution (when stored blocks have all
been executed during reverse execution, or when forward execution has not yet been performed),
operation stops. This is called the end of reverse execution.

Status indication

During reverse execution, characters "RVRS" blink on the screen. During forward reexecution, characters
"RTRY" blink to indicate that forward reexecution is in progress. The "RTRY" indication is kept blinking
until the block at which reverse execution started is reached and normal operation starts (until forward
execution is restarted).
When a block to be executed is no longer present during reverse execution, or if an attempt is made to
perform reverse execution for a block that cannot be executed by reverse execution, characters "RVED"
blink, notifying the user that reverse execution can no longer be performed.

Number of blocks that can be executed by reverse execution

Up to about 100 blocks can be executed by reverse execution. Depending on the specified program, the
maximum number of executable blocks may decrease.

Reset

A reset operation (the

key on the MDI unit, the external reset signal, or the reset & rewind signal)

clears the blocks stored for reverse execution.

Feedrate

A feedrate to be applied during reverse execution can be specified in parameter No. 1414. If this
parameter is set to 0, the feedrate in reverse execution is assumed to be the same as that in forward
execution. Rapid traverse, however, is performed always at the rapid traverse rate, regardless of the
setting of this parameter.
The feedrate in forward reexecution is always the same as that in forward execution.
In reverse execution or forward reexecution, feedrate override, rapid traverse override, and dry run are
allowed.

Start of reverse execution or forward reexecution after the end of a block

In a block for rapid traverse (G00), linear interpolation (G01), circular interpolation (G02, G03), dwelling
(G04), skip cutting (G31), or an auxiliary function in an automatic operation mode (memory operation,
part program operation, or MDI operation), reverse execution or forward reexecution can be started.
However, reverse execution and forward reexecution do not start as soon as the reverse execution signal
status is changed. When the block has ended, that is, after a movement, dwelling, or an auxiliary function
is completed, reverse execution or forward reexecution starts.

Start of reverse execution or forward reexecution after feed hold stop

When a feed hold stop operation is performed during execution of rapid traverse (G00), linear
interpolation (G01), circular interpolation (G02, G03), or skip cutting (G31), then the reverse execution
signal status is changed and operation is restarted, reverse execution or forward reexecution can be started

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immediately from the stop position. This cannot be performed when dwelling (G04) or an auxiliary
function is being executed.

Start of reverse execution

Feed hold stop
Reverse execution signal RVS = 1
Cycle start

Feed hold stop
Reverse execution signal RVS = 0
Cycle start

End of reverse execution, start of forward reexecution

Fig. 5.10 (j)

When reverse execution is started after feed hold stop operation, the part from the start point of that block
to the feed hold stop position is stored as one block. Therefore, when forward reexecution is performed
with the single block switch set to 1, a single block stop takes place as soon as the position at which
reverse execution started is reached.

Start of reverse execution or forward reexecution after single block stop

After a single block stop takes place, reverse execution or forward reexecution can be started immediately
when the reverse execution signal status is changed and restart operation is performed.

Limitation

Blocks that cannot be executed by reverse execution

In the modes listed below, reverse execution cannot be performed.
When one of these commands appears during reverse execution, reverse execution ends immediately and
"RVED" is displayed.
-

Cylindrical interpolation (G07.1,G107)

Polar coordinate command (G16)

Functions related thread cutting (G33,G34,G35,G36)

Polygon turning (G50.2, G51.2)

Tool axis direction control (G53.1)

Single direction positioning (G60)

Tapping mode (G63)

Tapping cycle (G84,G74)

Rigid tapping cycle (G84,G74,G84.2,G84.3)

Fine boring cycle (G76)

Back boring cycle (G87)

It is impossible to perform reverse execution for blocks specifying the commands listed below. If one of
these commands appears during reverse execution, reverse execution ends immediately and "RVED" is
displayed.
Some of these commands turn a mode on and off. It is possible to start reverse execution and perform
forward reexecution in a mode set by such a command. However, if a block that turns the mode on or off
is reached during reverse execution, the reverse execution ends at that block, and "RVED" is displayed.
-

Functions related AI contour control (G05,G05.1,G08)

HRV3 on/off (G05.4)

Inch/metric conversion (G20, G21)

Stored stroke check on/off (G22, G23)

Functions related reference position return (G27, G28, G29, G30)

3-dimensional coordinate system conversion (G68, G69)

Feature coordinate system (G68.2)

Figure copying (G72.1,G72.2)

Index table indexing

Cs contouring control

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Spindle positioning

Switching of automatic operation mode

When a single block stop operation is performed during reverse execution or forward reexecution and the
mode is changed from memory operation to MDI operation or vice versa, it becomes impossible to
perform reverse execution, forward reexecution, and forward execution. To restart operation, restore the
original mode, then perform a cycle start operation.

Single block stop position

A block that is internally generated by the control unit is also treated as one block during reverse
execution.

Path after compensation

Programmed path

<2>

<1>

Fig. 5.10 (k) Path when cutter compensation is applied

In the above example, the program specifies two blocks, but in actual operation, move commands for five
blocks are generated.
In such a case, positions at which a single block stop takes place may differ between forward execution
and reverse execution.

Positioning (G00)

When non-linear type positioning is performed (bit 1 (LRP) of parameter No. 1401 is set to 0), the tool
path in reverse execution and that in forward execution do not match. The tool path in forward
reexecution is the same as that in forward execution.
When linear type positioning is performed (bit 1 (LRP) of parameter No. 1401 is set to 1), the tool path in
reverse execution is the same as that in forward execution.

Forward
Reverse
Forward reexecution

Non-linear type positioning

(LRP = 0)

Linear type positioning

(LRP = 1)

Fig. 5.10 (l)

Dwell command (G04)

During reverse execution or forward reexecution, the dwell command (G04) is executed in the same way
as in normal operation.

Programmable data input (G10)

Tool compensation values, parameters, pitch error data, workpiece origin offsets, and tool life
management values set or modified by programmable data input (G10) are ignored during reverse
execution and forward reexecution.

Skip function (G31) and automatic tool length measurement (G37)

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The skip signal and the automatic tool length measurement signal are ignored during reverse execution
and forward reexecution. During reverse execution and forward reexecution, the tool moves along the
path that the tool has actually passed during forward execution.

Forward Reverse
reexecution execution

Forward execution
(Actual path)

Skip signal ON (G31)
or automatic tool length measurement signal ON (G37)

Signal not applied (G31)
(Programmed path)

Fig. 5.10 (m)

Setup of a coordinate system (G92, G54 to G59, G54.1P_, G52, and G92.1)

As for the display of the absolute coordinate value under reverse motion, the value in the work coordinate
system when reverse motion begins is displayed. Therefore, when the command (G92, G54 to G59,
G54.1P_, and G52) to which the work coordinate system is changed is passed, a different value might be
displayed as forward movement. However, the actual machine position does not differ.

Mirror image

When a block to which a mirror image is applied by programmable mirror image (G50.1, G51.1) is
executed during reverse execution, the tool moves along the actual path resulting from the application of a
mirror image in the reverse direction.
When a mirror image is applied to a block by setting or a machine signal, the block with the mirror image
not applied is stored. Mirror image application by setting or a machine signal is enabled also during
reverse execution and forward reexecution. Therefore, during reverse execution and forward reexecution,
the mirror image by setting data or machine signal must be turned on and off so that this on/off status and
the on/off status during forward execution match.

Changing offsets

Even when cutter compensation offsets or tool length offsets are changed during reverse execution or
forward reexecution, the change in compensation or offset data does not become valid until forward
reexecution ends and normal operation starts. Until then, the tool moves with the offset data that was
applied when the block was executed for the first time during forward execution.

Feedrate clamp

During reverse execution or forward reexecution, feedrate clamp is not performed with parameter No.
1420 (rapid traverse rate) or parameters Nos. 1430 and 1432 (maximum cutting feedrate). It is executed
with parameter No. 1414 or at the feedrate assumed during forward execution.
If, for example, the parameters above are set to smaller values during reverse execution or forward
reexecution, clamp is not performed with these values, but with parameter No. 1414 or at the feedrate
assumed during forward execution.
For clamp at the feedrate assumed during backward execution or forward reexecution, change the feedrate
with the external deceleration or override signal.

Interrupt type custom macro

(1) Do not initiate any interrupt during reverse execution.
(2) Do not execute an interrupted block and the interrupt program in reverse execution.

Tool management function

The tool life is not counted during reverse execution and forward reexecution.

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Inverse time feed (G93)

If a nonzero value is set as the feedrate to be applied during reverse execution in parameter No. 1414, a
block that moves the tool by inverse time feed during forward execution is executed at the parameter-set
feedrate (feed per minute) during reverse execution.
If the feedrate during reverse execution (parameter No. 1414) is not set (= 0), the same feedrate as applied
during forward execution is used.

Maximum spindle speed clamp (G92Sxxxx)

Clamping at a maximum spindle speed specified during reverse execution becomes valid. This means that
if G92Sxxxx appears during reverse execution, the spindle speed is clamped at Sxxxx in the subsequent
reverse execution. As a result, the clamp speed may differ between reverse execution and forward
execution even when the same block is executed. The spindle speed is clamped when the G96 mode is
set.

Auxiliary functions

M, S, T, and the second auxiliary function (B function) are output directly also during reverse execution
and forward reexecution.
When specified together with a move command in the same block, M, S, T, and the second auxiliary
function (B function) are output with the move command at the same time during forward execution,
reverse execution, and forward reexecution. Therefore, the output positions of M, S, T, and the second
auxiliary function (B function) during reverse execution differ from those during forward execution and
forward reexecution.

Custom macro

Custom macro operations are ignored during reverse execution and forward reexecution.

Execution macro (macro executor)

Macro executor operations are ignored during reverse execution and forward reexecution.

Tool retract and recover function

For retract operation and repositioning operation by the tool retract and recover function, reverse
execution cannot be performed. Retract operation and repositioning operation are ignored during reverse
execution and forward reexecution.

AI contour control

When the reverse execution is started in AI contour control mode, a reverse execution ends immediately
depending on a program then the reverse motion is not possible.
During reverse execution and forward reexecution, the feedrate clamp function by acceleration under AI
contour control is disabled.

Display

During reverse execution and forward reexecution, the modal display and the display of the currently
executed program are not updated; information obtained at the start of reverse execution is maintained.

Signal

Reverse execution signal RVS<Gn007.0>

[Classification] Input signal

[Function] Requests the control unit during automatic operation (DNC operation and MDI operation

except memory operation and binary operation) to return the tool by retracing the path the
tool has passed so far.

[Operation] When this signal is set to “1” during forward execution, the machining path along which

the tool has moved so far is retraced. Note that, however, reverse execution does not start
as soon as this signal is set to “1”; reverse execution starts after the forward execution of
the current block ends. When this signal is set to “0” during reverse execution, switching

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from reverse execution to forward reexecution takes place. Also in this case, forward
reexecution does not start as soon as the signal is set to “0”, but forward reexecution starts
after the reverse execution of the current block is completed.
To make swift switching from forward execution to reverse execution or from reverse
execution to forward reexecution, set the automatic operation stop signal *SP to 0 to stop
automatic operation, and after the automatic operation in-progress signal STL becomes
“0” and the automatic operation stop state is entered, change the RVS signal status.
Subsequently, after the automatic operation stop signal *SP is set to “1” and the status of
the automatic operation in-progress signal ST is changed from “1” to “0” to start
automatic operation, it becomes possible to change the execution mode to reverse
execution or forward reexecution in the middle of a block.

Reverse execution in-progress signal RVSL<Fn082.2>

[Classification] Output signal

[Function] Posts that reverse execution is being performed.

[Output cond.] This signal is set to “1” when:

The reverse execution signal RVS is set to “1” and reverse execution is being
performed.

This signal is set to “0” when:
-

The reverse execution signal RVS is set to “0” and forward reexecution or forward
execution is being performed.

Blocks to be executed are no longer present during reverse execution, and so
execution is stopped.

During reverse execution, the M, S, T, and second auxiliary functions are executed in the
same way as during forward execution. When these functions are not to be performed in
the same way as during forward execution, use this signal to allow the PMC to perform
appropriate processing.
In particular, when the M, S, T, or second auxiliary function and a move command are
specified in the same block, the positions at which the code signal and strobe signal are
output differ between forward execution and reverse execution. Therefore, use this signal
and distribution completion signal DEN to allow the PMC to perform appropriate
processing as necessary.

End of reverse execution
Start of forward reexecution
(Reverse execution signal RVS set to 0)

During reverse execution, auxiliary function is output here.

Block containing move command and auxiliary function

Start of reverse execution
(Reverse execution signal RVS set to 1)

During forward execution, auxiliary function is output here.

Fig. 5.10 (n)

Signal address

Gn007

RVS

Fn082

RVSL

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Parameter

1414

Cutting feedrate for reverse motion

[Input type] Parameter input

[Data type] Real path

[Unit of data] mm/min, inch/min, deg/min (machine unit)

[Min. unit of data] Depend on the increment system of the reference axis
[Valid data range] Refer to the standard parameter setting table (C)

(When the increment system is IS-B, 0.0 to +999000.0)
Set a cutting feedrate for retrace operation. When 0 is set, a retrace operation is performed
at a programmed feedrate.

NOTE

This parameter has no effect on blocks that are in rapid traverse
mode during reverse execution.

Warning

WARNING

1 Auxiliary functions are output directly even during reverse execution and forward

reexecution. Accordingly, note that the execution status of an auxiliary function
during forward execution may be reversed during reverse execution.
Example:

When forward rotation of the spindle(M03) and stop (M05) are specified.
When N3 is executed during reverse execution, M05 is output. So, when N2
and N1 are executed during reverse execution, operation is performed with
the spindle stopped.
When N1 is executed during forward reexecution, M03 is output. So, when N1
and N2 are executed during forward reexecution, operation is performed with
the spindle rotating in the forward direction.

M03 (forward spindle
rotation)

Forward spindle rotation

Forward

Reverse

Forward reexecution

Start of reverse execution

Restart of forward
execution

M05 (spindle stopped)

Spindle stopped

Fig. 5.10 (o)

2 To perform reverse execution after a feed hold stop or single block stop

operation, be sure to restore the original position if manual intervention has been
performed after the stop , then set the reverse execution signal to 1. Movements
made by manual intervention are ignored during reverse execution and forward
reexecution. (The same operation as in the manual absolute off state takes
place.)

If manual intervention is performed during reverse execution or forward
reexecution, the amount of manual intervention is added to the coordinate system
at a restart after a stop due to a feed hold or single block during forward
execution after the end of forward reexecution. Whether to add the amount of
manual intervention follows the manual absolute signal *ABSM <Gn006.2>.

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