Add or subtract that distance (converted to encoder pulses based on your machine resolution) to the existing parameter value. Type the new number and press 4. Cycle Power and Test Turn Parameter Write Enable (
Some of the most commonly used OT reference parameters in FANUC systems include:
Look at : This defines the grid shift and reference point shift.
| Problem | Most Likely Cause | Recommended Parameter Action | | :--- | :--- | :--- | | Axis overtravels during reference return (Alarms 510/511) | Software limit interference with reference return sequence | Temporarily set parameter No. 700 or 704 to ±99999999; restore after successful return | | Reference point shifts after power cycle (absolute encoder) | APZ bit not properly set or encoder batteries failed | Verify parameter No. 1815 APC and APZ bits are correctly configured; replace batteries and repeat absolute setup procedure | | Axis stops at inconsistent positions each reference return | Grid shift parameter incorrect for mechanical position | Adjust parameter No. 1850 in small increments (5–10 units) and verify consistency | | Reference return fails to complete (timeout) | Return speed too slow; deceleration switch failure | Increase parameter No. 534 and inspect physical deceleration switch operation | | Axis moves away from reference when G28 is commanded | Reference direction parameter incorrect | Verify ZMI bit (No. 1006, bit 5) matches the mechanical reference approach direction | fanuc ot reference parameter better
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What are your for the parameters you want to change?
Typically, parameter 700 (X), 701 (Z), 702 (3rd), 703 (4th) are used to set the distance from the reference mark to the actual tool position. 3. Adjusting the "Grid Shift" (A "Better" Method) Add or subtract that distance (converted to encoder
You have changed a servo motor, encoder, or ball screw.
Measures the physical slop when an axis reverses direction. Dialing this in precisely with a test indicator eliminates flat spots on turned diameters and keeps parts round.
: Parameter 902 Bit 6 enables "Custom Macro A," which is vital for complex automated routines. 3. Reference Point & Zero Return Parameters | Problem | Most Likely Cause | Recommended
Turn the control power off and back on to allow the system to load the modified parameters into its active memory. Best Practices for Long-Term Backup Management
By following the procedures outlined in this guide — from basic parameter configuration to advanced grid shift tuning — you can achieve significantly better reference return performance on your FANUC OT-controlled equipment. Whether you're dealing with incremental dog-type systems or modern absolute encoder configurations, the principles remain the same: understand the parameters, set them correctly, verify the results, and document everything.