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Locate M140 in NC program

Open the NC program in Program Run or Test Run mode. Use the search function (GOTO block number or FIND function) to locate all instances of M140 in the active program.

In Test Run mode, use the 'Search' softkey and enter 'M140' to quickly find all occurrences without manual scrolling.

Identify correct facing slide M-code

Check machine manufacturer's programming manual for the correct M-code used for tool retraction on facing slide. Common alternatives include M141, M142, or manufacturer-specific codes like M340-M349 range.

The correct M-code is often documented in MOD > Machine Parameter > M-Function Table or in PLC marker assignments M4300-M4500.

Replace M140 with correct M-code

Edit the NC program and replace M140 with the manufacturer-specified facing slide retraction M-code. Save the modified program and reset the alarm with CE key.

Test the modified program in single block mode first to verify proper facing slide movement.

Verify program execution

Run the program in Test Run mode or with dry run active to confirm the facing slide retracts correctly without triggering the alarm. Monitor axis positions on the position display.

Use the 'Program Test' function (MOD > Program Test) to simulate the complete program without axis movement if available on your control version.

Review post-processor output

Examine the generated NC code from your CAM system. Identify where M140 is being inserted - typically during tool change sequences, rapid retract moves, or end-of-program sequences.

Most CAM systems insert M140 during 'retract to clearance' or 'tool change' operations in the post-processor logic.

Obtain machine-specific post-processor

Contact your machine tool builder or CAM vendor for a post-processor specifically configured for facing slide equipped machines. This post will use the correct M-codes defined by the machine manufacturer.

Request the machine model number and control version when obtaining the post - facing slide M-codes vary by machine builder.

Modify existing post-processor

If custom post modification is needed, edit the post-processor to replace M140 output with the correct facing slide M-code. This typically requires changing the 'on_retract' or 'on_toolchange' post functions.

Always test modified post-processors thoroughly on non-critical programs before production use.

Regenerate and verify NC code

Re-post the toolpath with the updated post-processor. Verify that the new NC code contains the correct facing slide M-codes and no M140 instances remain. Test run the program before production.

Create a test program with multiple tool changes to fully validate the post-processor changes across different scenarios.

Check PLC M-function configuration

Access MOD > Machine Parameter and review MP7440.x settings for M140 configuration. Check if M140 is defined as type 4 (synchronized) or blocked when specific PLC markers are active.

On iTNC 530 and TNC 640, you can view active PLC markers in MOD > PLC > Marker Display to see facing slide status bits.

Review PLC program M140 handling

If you have access to PLC source (service level), examine the M-function module handling M140. Look for conditional logic that checks facing slide configuration markers (typically M4xxx range) and blocks M140 execution.

PLC program access requires service-level password. Do not modify PLC logic without machine builder approval and backup.

Verify facing slide parameters

Check machine parameters related to facing slide configuration (varies by machine builder, often MP1xxx or custom OEM parameters). Confirm facing slide is properly configured and active markers match physical machine configuration.

Document all parameter values before any changes. Incorrect facing slide parameters can cause serious kinematic errors.

Contact machine builder support

If M140 blocking is by design for your facing slide configuration, contact the machine tool builder for guidance on proper programming methods. Request documentation on approved M-codes for tool retraction with facing slide active.

Have machine serial number, control software version (check in MOD > System Info), and PLC version ready when contacting support.