Fanuc Alarm 157: TOO MANY TOOL GROUPS

Fanuc Control Model: Fanuc 16i / 18i / 21i Series & 0i / 30i / 31i Series

Official Alarm Description

The number of tool groups to be set exceeds the maximum allowable value. (See parameter No. 6800 bit 0 and 1) Modify the program

Common Causes

This alarm is typically triggered when setting up tool life management or tool group programming:

• Exceeding Parameter Limits: Setting up more tool groups in the control system than the option parameter allows.
• Unused Groups Not Cleared: Retaining old or unused tool groups in the controller memory without deleting them before registering new ones.
• Program Syntax Error: Specifying a group number (H or D code associated with tool life management) higher than the machine’s configured range in the G-code program.
• Option Parameter Restriction: Attempting to use expanded tool management features without the appropriate Fanuc software option installed.

Step-by-Step Troubleshooting & Solution

Follow these steps to clear Alarm 157 and resume machine operation:

1. Access Tool Management Screen: Press the OFFSET / SETTING key on the MDI panel and navigate to the TOOL LIFE or TOOL GROUP display screen.
2. Check Current Groups: Inspect the list of active tool groups to see if the maximum allowable index has been reached.
3. Delete Unnecessary Groups: Clear or delete unused tool groups from the memory to free up slots for the new group.
4. Inspect G-Code Program: Switch to EDIT mode and verify the tool group numbers specified in your active program. Ensure no invalid group number is being called.
5. Clear Alarm: Press the RESET button on the MDI panel to clear the alarm status.

G-Code Example (Correct vs Incorrect)

Incorrect Code: G10 L3 P25 

Correct Code: G10 L3 P12

Frequently Asked Questions (FAQs)

Q1: Can I increase the maximum allowed tool groups on my Fanuc controller?

The maximum limit is governed by Fanuc system parameters and option configurations. Increasing this limit usually requires activating option parameters through an authorized technician.

Q2: Is a full machine power cycle required to clear Alarm 157?

No. Simply clearing unused tool groups from the Tool Life screen or correcting the program data and pressing RESET will clear the alarm.