FANUC PS0205 Alarm: Rigid Mode DI Signal Off

FANUC PS0205 means that the CNC reached a rigid-tapping cycle but did not receive the required rigid-mode confirmation DI signal from the PMC. On the FANUC systems covered by the newer alarm documentation, this confirmation is identified as RGTAP <G061.0>. If it is not ON when the CNC executes the applicable G84 or G74 block, the CNC stops with PS0205 / RIGID MODE DI SIGNAL OFF.

The primary fault area is the machine-tool builder's PMC sequence and its rigid-tapping signal handling. On a multi-spindle or multi-path machine, incorrect spindle selection, path assignment, or use of a spindle already controlled by another path can also generate PS0205.

For the preceding program-sequence alarm, see the FANUC PS0204 Illegal Axis Operation guide. For the broader list, see FANUC CNC Alarm Codes 0201–0400.

Safety Warning Before Checking the PMC Sequence

Rigid tapping synchronizes spindle rotation with tapping-axis movement. Incorrectly forcing a PMC signal, bypassing an interlock, selecting the wrong spindle, or testing with an unsafe tool position can cause unexpected spindle or axis motion, break the tap, and damage the workpiece or machine.

Do not force RGTAP ON merely to clear PS0205. Do not edit the production ladder while the machine is available for automatic operation. PMC diagnosis and ladder changes must be performed by qualified personnel using the exact FANUC connection manual, machine-builder ladder documentation, original PMC backup, and an approved test procedure.

Record the alarm, program, PMC status, machine state, and original ladder before making any change. Perform the first test without a workpiece and, where the machine builder permits, without a cutting tool. Keep the enclosure closed and use the machine builder's controlled verification procedure.

What Does FANUC PS0205 Mean?

FANUC's alarm description states that a rigid M code—commonly M29—has been specified, but the rigid-mode DI signal is not ON when the G84 or G74 rigid-tapping block is executed. The official direction is to check the PMC sequence program and determine why the signal was not turned ON.

This means the CNC has recognized the rigid-tapping request in the NC sequence, but the machine-side control sequence has not returned the expected confirmation at the required time. The alarm can occur when:

• The ladder never turns the rigid-mode confirmation ON.

• The ladder turns it ON too late, after the CNC checks the signal.

• The signal turns ON briefly but drops before the tapping-cycle block is executed.

• A permissive or interlock in the machine-builder sequence prevents the signal from being set.

• The program uses a rigid M code that the CNC recognizes but the machine-builder ladder does not process as expected.

• A multi-spindle or multi-path configuration does not identify one valid spindle for the current tapping command.

PS0205 is therefore different from a normal M29/G84 formatting error. A correct-looking program can still produce the alarm if the PMC-CNC handshake or spindle-selection sequence is incomplete.

G061.0 Is a PMC Address, Not an NC G Code

The notation G061.0 or G61.0 in this alarm refers to a bit in the FANUC PMC-to-CNC signal area. It is not a G61 exact-stop command and it is not an instruction that should be added to the NC program.

On FANUC PMC systems, a G-address signal is generally sent from the PMC to the CNC. FANUC calls RGTAP a DI signal from the CNC's point of view because it is an input received by the CNC. From the ladder's point of view, however, the machine-builder PMC logic drives the G-address bit.

Do not attempt to correct PS0205 by writing a line such as G61.0 in the part program. That would confuse a PMC address with an NC command and would not repair the missing rigid-mode confirmation.

How the Rigid-Tapping Confirmation Sequence Works

The exact ladder differs by machine builder, but the control relationship is generally:

If stage 3 is missing, late, or canceled before stage 4, PS0205 occurs. The purpose of troubleshooting is to find the condition that prevents this sequence from completing—not simply to hold the output bit ON permanently.

1. Record the Exact Alarm and Machine Configuration

Before changing the program or ladder, record:

• The complete alarm message and number

• The exact FANUC CNC series, model, and software series

• Whether the machine is an M series or T series

• The active path and commanded spindle

• The machine-builder model and ladder version

• The rigid-mode M code used by a verified working program

• The program blocks before and including M29 and G84/G74

• The RGTAP signal state before M29, after M29, and at the tapping-cycle block

• The spindle-selection signals on a multi-spindle machine

• Any recent PMC, parameter, CNC, spindle, machine, or post-processor changes

The moment at which RGTAP changes is more useful than a single static screenshot. If the signal is ON after the alarm but was OFF when G84 was checked, a static check can hide the timing fault. Use the ladder status, signal trace, or diagnostic recording method approved for the exact control.

2. Confirm the Machine's Approved Rigid-Tapping Command Method

M29 is the common FANUC rigid-mode M code, but it is not universal. Applicable FANUC parameters allow a different M code, and some configurations can enter rigid mode automatically with the tapping-cycle command. The machine builder's ladder must match the configured command method.

A common program form is:

G00 X50.0 Y30.0 Z5.0
M29 S500
G84 Z-20.0 R2.0 F1.25

The numerical values are examples only. Use the actual speed, feed mode, thread lead, depth, and clearance approved for the machine and tool.

Compare the alarm program with a known-good rigid-tapping program from the same machine. If the machine normally uses another M code, do not substitute M29 only because it appears in a generic FANUC example. A mismatch can allow the CNC to interpret the rigid-tapping request while the custom ladder fails to complete the intended machine sequence.

Do not change the rigid-mode M-code parameter until the CNC parameter backup, ladder logic, machine-builder documentation, and working program have been compared. The parameter and PMC sequence must agree.

3. Monitor RGTAP at the Required Time

On systems that identify the signal as RGTAP <G061.0>, monitor the bit through the complete test sequence:

1. Before the rigid M code, confirm its normal idle state.

2. Execute the approved rigid M-code block under the controlled test procedure.

3. Confirm whether RGTAP turns ON after the PMC recognizes the request.

4. Confirm that it remains in the required state when the G84/G74 block is executed.

5. After the cycle is canceled, confirm that it clears according to the applicable FANUC and machine-builder sequence.

The result separates several possible faults:

• Never ON: the M-code decode, permissive logic, spindle selection, or output rung is incomplete.

• ON too late: the M-code completion and RGTAP timing may be in the wrong order.

• ON then OFF before G84: a drop-out condition, incorrect latch, or premature cancel path is active.

• Correct at G061.0 but PS0205 remains: verify the exact address and alarm definition for that CNC series rather than assuming the machine uses the newer signal mapping.

FANUC parameter manuals also describe a cancellation relationship between RGTAP and the CNC's exit from rigid mode. The exact order can depend on the applicable setting and control series. Do not rewrite the latch or cancellation logic from a generic online diagram.

4. Trace the PMC Ladder From the Rigid M Code to RGTAP

If RGTAP does not turn ON correctly, trace the ladder backward from the RGTAP coil or output condition. Identify every contact and function block that must be satisfied.

Depending on the machine builder, the rung may include conditions for:

• Recognition of the configured rigid-tapping M code

• Automatic or MDI operating mode

• Selected spindle and selected path

• Spindle-control mode

• Gear range or orientation completion

• C-axis or rotary-tool mode cancellation

• Servo-ready, spindle-ready, or machine-ready status

• Chuck, turret, tool, door, or other builder-defined interlocks

• Completion and reset conditions for the auxiliary function

• Internal relays used to latch and cancel rigid mode

These are possible machine-builder logic elements, not a universal FANUC checklist. Record which contact is actually open on the affected machine and determine why. Do not bypass an open condition without understanding its purpose.

Compare the current ladder with the original backup when the alarm began after:

• CNC or PMC replacement

• Ladder restoration or editing

• Parameter initialization or restore

• Addition of a spindle, live tool, or rotary axis

• Machine retrofit

• Software update

• Loss of PMC keep-relay data

If the ladder has always worked and no logic or parameter change occurred, inspect the actual input condition that now prevents the established rung from completing. The alarm still identifies the missing confirmation; it does not prove that the ladder source code itself was recently altered.

5. Check M-Code Completion and Signal Timing

The rigid M code and its auxiliary-function completion must be coordinated with the RGTAP confirmation. If the ladder returns M-code completion before the rigid-mode confirmation is valid, the CNC may advance to the G84/G74 block and check RGTAP while it is still OFF.

Conversely, if RGTAP is generated only as a short pulse instead of being maintained for the required part of the sequence, the bit may disappear before the CNC performs the check. Review the ladder time chart and the actual status transition rather than checking only whether the signal changes at some point.

Do not solve a timing problem by adding an arbitrary timer. The correct order depends on the control series, PMC execution, auxiliary-function handshake, spindle selection, and machine-builder specification. Identify the real missing or premature condition first.

6. Check Multi-Spindle and Multi-Path Selection

On a multi-spindle machine, RGTAP can be correct while PS0205 is generated because the CNC cannot identify one valid spindle for the current path and rigid-tapping command.

The FANUC Series 500i-A maintenance manual lists these additional PS0205 conditions:

• No spindle is found that accepts the command for the active path.

• Spindles in multiple paths select commands from the same path incorrectly.

• The spindle specified for rigid tapping is already operating under another path.

• The rigid-tapping spindle is not selected on a multi-spindle system.

• A rigid-tapping command is issued for a servo-motor rotary-tool axis assigned to another path.

Check the active path, commanded spindle, spindle command-select signal, and any path/spindle ownership logic before editing RGTAP.

On applicable Series 16i/18i multi-spindle controls, FANUC documentation describes two possible spindle-selection methods:

Which method applies depends on the exact control, options, parameters, and machine-builder design. Other FANUC generations can use different signal counts or path-assignment methods. Do not force SWS or RGTSP bits and do not change the selection-method parameter without the applicable manual and original machine data.

7. Account for FANUC Series and Address Differences

The alarm meaning is consistent, but the displayed address and the list of additional conditions are not identical in every FANUC generation.

The leading zero and separator style may also vary, such as G61.0, G061.0, or <G061#0>. These can describe the same byte-and-bit notation within a particular documentation family, but G061.0 and G061.1 are different bits. Verify the exact control before tracing or editing the ladder.

M-series and T-series tapping-cycle references can differ as well. Many M-series manuals refer to G84/G74, while applicable older T-series alarm lists may refer to G84/G88. Use the machine's operator manual rather than copying a cycle from another control type.

8. Do Not Start With Spindle Hardware Replacement

PS0205 does not directly diagnose a failed spindle amplifier, spindle motor, position coder, encoder cable, servo amplifier, or CNC main board. FANUC's primary corrective direction is to inspect the PMC sequence and, where applicable, spindle/path selection.

A separate hardware or spindle alarm may explain why a ladder permissive remains OFF, but PS0205 alone is not evidence for replacing that hardware. Diagnose the additional alarm or the specific open ladder contact before selecting a part.

Similarly, do not change rigid-tapping gain, acceleration, backlash, maximum-speed, or position-coder parameters to clear a missing DI confirmation. Those settings affect other rigid-tapping functions and alarms; they do not replace the PMC-to-CNC RGTAP handshake.

Difference Between PS0204, PS0205, and PS0206

The presence of M29 and G84 in the correct order does not exclude PS0205. PS0204 focuses on the NC sequence, while PS0205 focuses on confirmation of the requested machine mode and the selected spindle.

FANUC PS0205 Diagnostic Table

Recommended Troubleshooting Order

1. Confirm PS0205 / RIGID MODE DI SIGNAL OFF and record the full alarm screen.

2. Identify the exact FANUC CNC series, software, M/T system, active path, machine model, and ladder version.

3. Record the approved rigid-tapping M code and the program blocks through G84/G74.

4. Compare the program with a known-good rigid-tapping program from the same machine.

5. Identify the exact RGTAP address for that control; do not assume every system uses G061.0.

6. Monitor the signal before the rigid M code, after the M code, and when the tapping-cycle block is executed.

7. If the signal never turns ON, trace the ladder from RGTAP backward through every actual open condition.

8. If the signal is late or drops early, check M-code completion, latch, reset, and cancellation timing.

9. On multi-spindle or multi-path systems, verify the selected spindle, command path, ownership, and applicable SWS/RGTSP or spindle command-select signals.

10. Compare the PMC, parameters, and keep data with the original backup if the alarm followed a restore, replacement, update, or retrofit.

11. Do not force G061.0, bypass interlocks, or change ladder logic without qualified review and machine-builder documentation.

12. Do not replace spindle hardware or alter rigid-tapping tuning parameters unless another alarm or measured condition supports that diagnosis.

13. After correction, verify the complete rigid-mode entry and cancellation sequence, then perform a controlled test without a workpiece before cutting.

Technical References

• FANUC Series 500i-A Maintenance Manual, B-64805EN/03, PS0205 alarm definition, RGTAP <G061.0>, and multi-path/multi-spindle conditions

• FANUC Series 30i/31i/32i Model A Maintenance Manual, B-63945EN/02, PS0205 alarm definition and DGN G061.0

• FANUC Series 0i-MODEL D / 0i Mate-MODEL D Maintenance Manual, B-64305EN, PS0205 alarm definition

• FANUC Series 0i-MODEL D / 0i Mate-MODEL D Connection Manual (Function), B-64303EN-1, rigid-tapping CNC/PMC signals and sequence

• FANUC Series 16i/18i/160i/180i Model B Parameter Manual, B-63530EN/03, RGTAP cancellation and SWS/RGTSP multi-spindle selection

• FANUC Series 16i/18i/21i Model B Operation and Maintenance Handbook, B-63527EN/01, RGTAP <G61#0> and multi-spindle PS0205 conditions

• FANUC Series 16i/18i/160i/180i Model A Maintenance Manual, B-63005EN, legacy PS0205 signal notation

• Beijing FANUC technical guidance for PS0205: rigid tapping mode DI signal off

Always use the manual edition that applies to the exact CNC, software, machine type, PMC, ladder, spindle count, path configuration, options, and machine-builder interface.

Need Help With FANUC PS0205 Alarm?

REACO CNC provides independent FANUC technical support, PMC sequence review, drive testing, repair, and parts compatibility checking. Send us the PS0205 alarm screen, complete CNC and machine models, ladder version, program blocks around the rigid M code and G84/G74, RGTAP status, selected path and spindle, and details of any recent PMC, parameter, CNC, spindle, or machine changes.

Visit the FANUC Technical Support Center for more FANUC alarm guides, or contact REACO CNC for assistance.

Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The correct signal address, ladder sequence, spindle-selection method, and verification procedure depend on the exact CNC, PMC, software, machine, options, and machine-builder specification.