Setting Default Speed and Termination

Understand the four parts of a motion instruction

A motion line specifies a motion format (J, L, C, or A), position data, a feed rate, and a positioning path such as FINE or CNT. A sample line reads 4: L P[3] 500mm/sec CNT10. Speed and termination are the two arguments this guide sets.

Review the application's accuracy needs

Decide which points require an exact stop, for example a pick, a place, or a process start, and which are only intermediate via points that can round the corner. Points that need precision get FINE; via points get CNT for smoother, faster motion.

Set standard motion defaults so new lines inherit them

On the program edit screen press F1 POINT, then F1 ED_DEF to open the Default Motion screen. It lists the standard statements such as J P[] 100% FINE, J P[] 100% CNT100, L P[] 100mm/sec FINE, and L P[] 100mm/sec CNT100. Editing these means every newly taught line starts from your preferred speed and termination.

Edit a default value on the Default Motion screen

Move the cursor to the item to change (motion type, feed rate, or positioning type). For feed rate, type a new number and press ENTER; for positioning type, press F4 CHOICE and pick Fine or Cnt. Repeat for each standard statement, then press F5 DONE.

Select the motion line to edit

To tune an existing line, move the cursor to it, or press the ITEM key and enter the line number to jump straight there. The cursor must sit on the argument you intend to change.

Set the feed rate for joint motion

For a joint (J) move, the feed rate is a percentage of maximum feed rate from 1 to 100 percent. You can instead specify time in sec (0.1 to 3200) or msec (1 to 32000) when the duration of the move matters more than a percentage. Move the cursor to the feed rate argument, type the value, and press ENTER.

Set the feed rate for linear or circular motion

For linear (L), circular (C), or circle arc (A) moves, choose a unit and value: mm/sec (1 to 2000), cm/min (1 to 12000), or inch/min (0.1 to 4724.4). Pure rotation about the TCP is specified in deg/sec (1 to 272). Time units sec and msec are also available for these formats.

Know that changing motion type changes the speed unit

When you change the motion type on a line, the feed rate unit changes automatically, for example from percent to mm/sec. Recheck the numeric value after any motion-type change so the speed is still what you intend. The feed rate is not converted for you when the unit changes.

Choose FINE for points that need an exact stop

With FINE the robot stops at the target point before it moves to the next point. Press F4 CHOICE on the positioning argument and select Fine (Motion modify: 1 Fine, 2 Cnt). Use FINE at pick, place, and process points, and wherever the next line changes the reference frame or direction.

Choose CNT for via points that can be rounded

With CNT the robot approaches the target but does not stop, then continues to the next point. Select Cnt from the CHOICE menu and enter a value from 0 to 100. This blends the corner and removes the stop-and-go dwell that FINE adds at every point.

Tune the CNT value for the path shape you want

CNT0 drives the nearest path to the point and moves on without stopping, so the corner stays tight. CNT100 rounds the widest because the robot does not decelerate near the point and leaves for the next point soonest. Pick a smaller value for a tighter path and a larger value for a smoother, wider corner.

Adjust acceleration if motion is too abrupt

The ACC additional instruction sets the acceleration and deceleration rate as a percentage, for example J P[1] 50% FINE ACC80. Lowering ACC below 100 stretches the acceleration time and gives gentler starts and stops, which suits delicate loads such as scooping liquid. Add it from the Motion Modify menu (item 3, ACC).

Test the motion at reduced speed first

Set the teach pendant feed rate override low and step or run the changed lines before you go to production speed. The override key cycles VFINE, FINE, 1, 5, 50, and 100 percent, and it scales the programmed feed rate during execution. Watch the actual path and the stop points before raising the override.

Fine-tune after observing the real path

Adjust the speed and CNT values based on how the tool tracks the corners and how the change affects cycle time. Tighten CNT where the path cuts a corner too wide, and raise it where you want more blending. Re-verify at reduced speed after each change.

What can go wrong: the robot still stops at a CNT point

If a WAIT or similar instruction follows the move, the robot stops at the point to execute it even with CNT specified. The WAIT at Taught Position setting, when TRUE, makes a WAIT after a CNT move behave as if BREAK were taught, so the robot decelerates to the point. Check for a trailing instruction and that setting before assuming the CNT value is wrong.

Caution: Do not remove an interlock or WAIT that guards a process step just to gain a rounded corner. Correct the sequence or accept the stop where the logic requires it.

What can go wrong: short fast segments decelerate anyway

Several short-distance, high-speed motions run continuously with CNT may still decelerate, even when the CNT value is 100. This is a limit of how far ahead the controller can blend, not a teaching error. Combine or lengthen segments, or accept the deceleration, rather than chasing it with higher CNT values.

What can go wrong: a programmed speed is rejected

The programmed traveling speed cannot exceed the allowable range of the robot, and a speed above the range raises a warning alarm. The maximum feed rate depends on the robot model, so a value that works on one arm may be too high on another. Lower the feed rate to within the model's range and re-teach the line.

What can go wrong: register-driven speed behaves unexpectedly

A feed rate given by a register, for example J P[1] R[i]% FINE, can move the robot at an unexpected speed if the register holds a surprising value. The value is not range-checked when you edit the line, so an out-of-range register triggers an alarm only at execution. Because read-ahead can pick up an old register value, interlock the logic and avoid changing the feed-rate register while the program runs.

Caution: Treat register-driven speed with care during both teaching and operation, and verify the resulting motion at reduced speed before production.

What can go wrong: raising ACC causes vibration or a servo fault

Acceleration above 100 percent can cause awkward motion or vibration and draws a large instantaneous current that may drop the input voltage. That can trigger a servo alarm such as a power alarm, position error excess, or servo amplifier low voltage. Over 100 percent also increases the load on the arm and shortens reducer life.

Caution: If such an alarm occurs, correct the cause first: reduce the acceleration override or delete the ACC instruction. Do not repeatedly reset and re-run through the fault at the same aggressive acceleration.