Robotics in Manufacturing
MOTN-161

MOTN-161: Cannot look ahead to next motion

The motion planner couldn't retrieve the next motion instruction to look ahead.

What it means

The motion planner couldn't retrieve the next motion instruction to look ahead. Certain program constructs block the controller from planning the upcoming move.

Common causes

Ranked by what technicians most often find, most likely first.

  1. Unlocked position registers used in the motion path.
  2. Conditional branching with IF or SELECT statements interrupting the look-ahead.
  3. Control transfer to another program.
  4. Changing a system variable setting from within the program.

How to fix it

  1. Use the LOCK PREG instruction to lock position registers.
  2. Remove IF or SELECT conditional branching where possible.
  3. Consolidate separate programs into one where possible.
  4. Move the parameter (system variable) instruction to a different line if possible.

Quick facts

Category
Motion
Affected series
R-30iB; R-30iB Mate; R-30iB Plus; R-30iB Mate Plus
Alarm family
MOTN

Verified against FANUC documentation (B-83284EN-1).Last reviewed: 2026-07-12.Editorial process