1A0-008B

Locate the problematic FN18 call

In MANUAL mode, press the PROGRAM TEST key and review the error location. Note the exact line number and FN18 syntax. The alarm typically shows which block triggered the error.

Use Test Run with single-block mode to step through the program and see Q-parameter values in the calculator before the FN18 executes.

Check machine axis configuration

Access MOD function, select 'Machine Parameters', and review MP120 (number of axes) and the axis assignment table. Note the total number of controlled axes (typically 3-5 axes).

Valid axis indices typically range from 1 to the value in MP120. Some FN18 implementations use 0-based indexing.

Verify FN18 syntax and index value

Review the FN18 call structure: FN18: SYSREAD Q-parameter ID-number IDX-parameter. Check that the IDX value (axis index) is within the valid range 1 to MP120 value. If using a Q-parameter for the index, verify its calculated value.

Add a temporary programming line before FN18 like 'FN16: F-PRINT Q-par/text' to output the axis index value to verify calculation.

Correct the axis index or program logic

Either change the hardcoded axis index to a valid value, or if using Q-parameters, correct the calculation logic. For portable programs, add conditional logic to check MP120 value first before calling FN18 with axis-specific IDs.

Use FN18 ID10 to read MP120 into a Q-parameter, then use conditional jumps (FN9/FN10) to skip axis reads that would exceed the configured axis count.

Identify the Q-parameter used as axis index

Examine the FN18 call and note which Q-parameter is used in the IDX position. For example: 'FN18: SYSREAD Q10 ID220 IDX Q5' means Q5 contains the axis index.

The axis index parameter follows the 'IDX' keyword in FN18 syntax and can be either a direct number or a Q-parameter.

Trace Q-parameter value calculation

Work backwards through the program from the FN18 call to find where the axis index Q-parameter is calculated or assigned. Check for arithmetic operations, loop counters, or FN18 reads that populate this parameter.

Use the TNC's integrated programming station or Test Run mode with Q-parameter display active to monitor parameter values during execution.

Test parameter value before FN18

Insert a temporary 'FN16: F-PRINT Q-parameter/"Axis Index="' statement immediately before the FN18 call to output the actual value. Run in program test mode to verify the value without executing machine movement.

Ensure program test mode is active before running diagnostic code to prevent unintended machine movement.

Add parameter validation logic

Before the FN18 call, add conditional checks: Read MP120 into a Q-parameter, then use FN12 IF statement to verify the axis index is between 1 and the maximum axis count. Display an error message or skip the operation if invalid.

Standard validation pattern: 'FN18: SYSREAD Q50 ID10 / Q50=MP120 axis count / FN11 IF Q5 GT Q50 GOTO LBL 99 / FN12 IF Q5 LT 1 GOTO LBL 99'