MOTN-051

Identify the faulting program line

Press RESET to clear the alarm. Note the program name and line number displayed on the alarm screen. Press FCTN > Alarm > F1 HIST to view alarm history if needed. The line number shown indicates exactly where the invalid speed was encountered.

The alarm triggers on the motion instruction being executed, not on the line where a variable was set. Always trace back register assignments if using variable speeds.

Examine the motion instruction speed parameter

Navigate to MENU > SELECT > the program name > ENTER. Cursor to the flagged line number. Check the speed field in the motion instruction (e.g., J P[1] 50% FINE or L P[2] 250mm/sec CNT100). Verify the speed value is present and positive.

Do not modify programs while in AUTO mode. Switch to T1 or T2 mode before editing.

Check for register-based speed calculation

If the speed uses a register (e.g., R[10]%), navigate to MENU > DATA > REG > and locate the register number. Press ENTER to view the current value. Verify it contains a positive value. If R[10]=0 or negative, trace backward in the program to find the register assignment instruction (R[10]=...) and correct the calculation logic.

Use MENU > DATA > REG > TYPE > Position Reg to toggle between numeric and position registers. Speed calculations often use numeric registers R[x], not position registers PR[x].

Verify position register speed components

If using position register motion (e.g., L PR[5] R[10]%), ensure both the position register and speed register contain valid data. Check MENU > DATA > POSITION REG for PR validity. A common error is using an uninitialized register immediately after power-up or program reset.

Add register initialization logic at program start (R[10]=50) or use IF R[10]<=0 THEN R[10]=25 to create bounds checking before motion instructions.

Verify percentage speed range

Locate the motion instruction causing the alarm. If speed is shown as a percentage (e.g., 150% or -5%), this directly violates the valid range. Check if the speed is hardcoded or calculated via register. For hardcoded values, edit the instruction and change to a value between 1-100%.

Speeds above 100% may seem logical for override but are invalid in program instructions. Use the speed override dial on the teach pendant for temporary speed increases during teaching, not in program code.

Inspect register math for overflow conditions

If using calculated speeds (e.g., R[15]=R[12]+R[13] followed by L P[1] R[15]%), trace each register value. Navigate to MENU > DATA > REG and check R[12], R[13], and R[15]. If R[12]=60 and R[13]=50, then R[15]=110, exceeding 100%. Implement bounds checking: R[15]=R[12]+R[13]; IF R[15]>100 THEN R[15]=100; ENDIF.

Use system variable $FAST_CLOCK or production counters for dynamic speed? Always add min/max clamping logic: IF R[10]<1 THEN R[10]=1; IF R[10]>100 THEN R[10]=100.

Check for unitless vs percentage speed mismatch

Verify the motion instruction specifies the speed unit correctly. J P[1] 50% is valid, but J P[1] 50 (without %) may be interpreted incorrectly depending on system configuration. Check system variable $SCR.$SPEEDUNIT (MENU > SYSTEM > Variables > $SCR.$SPEEDUNIT) to confirm default speed units.

Always explicitly specify units in motion instructions (%, mm/sec, deg/sec, cm/min) to avoid ambiguity, especially in programs ported between different robot models.

Review conditional logic affecting speed registers

Search the program for IF/SELECT statements or subroutine calls that modify speed registers before motion. Use FIND (FCTN > FIND) to search for the register number (e.g., R[15]=). A conditional branch might set invalid values under certain input conditions. Test all program branches to ensure speed registers remain valid.

Enable MEMO > STATUS > Reg to display register values on screen during program execution in T1 mode for real-time debugging of calculated speeds.

Identify the robot model maximum speeds

Navigate to MENU > SYSTEM > Variables. Scroll to $DMR_GRP[1].$MAX_SPEED to view maximum TCP speed in mm/sec. For joint speeds, check $DMR_GRP[1].$JOINT_MAX_SPD[x] where x is joint number (1-6). Document these values as they represent absolute hardware limits that cannot be exceeded in programming.

Different robot models have vastly different limits: M-10iA may limit to 10,000 mm/sec TCP, while R-2000iC limits to 2,000 mm/sec. Always verify for the specific robot model on site.