Performing a FANUC Controlled Start

Back up before you change anything

Make a current backup of programs and system files. Controlled start exposes system variables and maintenance screens that can alter motion parameters, so a known-good backup lets you restore if a change goes wrong.

Confirm at least 600 KB of free FROM

The controller will not offer controlled start when free FROM drops below 600 KB. Check free space in the memory status menu (select MENU, 0 Next, 4 Status, Memory), and if it is low, remove unnecessary data from the FR: or FRA: device first.

Caution: The configuration menu hides the controlled start option when the rest of FROM is less than 600 KB.

Stop production and clear the cell

Confirm no program is running and that it is safe to power the controller down. Announce the shutdown and keep others clear of the robot.

Power off the controller

Shut the controller down using the normal procedure, then set the main power breaker to OFF.

Boot into the configuration menu

Hold the [PREV] and [NEXT] keys on the teach pendant while setting the controller power breaker to ON. Keep both keys held until the CONFIGURATION MENU appears.

Select "3 Controlled start"

From the menu (1 Hot start, 2 Cold start, 3 Controlled start, 4 Maintenance), choose 3. The controlled start menu loads as a simple system and opens the Tool Setup screen.

Caution: The controlled start menu cannot operate the robot; jogging and program execution are unavailable in this mode.

Open the screen you need from [MENU]

Press [MENU] to reach the controlled start screens: Tool Setup, Software Version, Variables, File, Alarm history, Port Init, Memory, Maintenance, Max. number setting, Password, and Host Communication. Only the screens in this simple system are available here.

Change a protected system variable, if that is the task

Press [MENU] and select "4 Variables". At controlled start you can edit variables that are read-only (R0) during normal operation, so change only the specific variable your task calls for.

Read a system file or restore a backup, if that is the task

Press [MENU] and select "5 File". At controlled start, F4 shows [RESTORE] and system files can be read that a normal file screen will not load; pressing F4 reads files, and "all of above" reads all files at once.

Caution: Restoring overwrites the controller's current programs and settings with the backup contents.

Switch F4 between RESTORE and BACKUP if needed

On the controlled start file screen, F4 defaults to [RESTORE]. To back up instead, press [FCTN] and select RESTORE/BACKUP to toggle F4.

Load files over a communication link, if that is the task

To load files by communication at controlled start, set up the serial port first. Use the Port Init screen and the Host Communication setting screen to configure the port before loading from the File screen.

Release a password restriction if a screen is locked

When settings are restricted by password level, the Password setting screen releases the restriction. Enter the password there to unlock the restricted setting for the session.

Adjust a memory allocation limit, if that is the task

The Max. number setting screen changes how many registers, macros, and user alarms the controller reserves. Some counts, such as the payload schedule count set through $PLST_SCHNUM, need the variable set, then a power cycle and a second controlled start before they apply.

Leave Maintenance alone unless reconfiguring the robot

The Maintenance screen changes mount type, payload mode, and extended axis. Running Robot Maintenance returns all motion parameters to default, so path, cycle time, and joint axis limits can change even if you touched nothing.

Caution: Enter Maintenance only when you intend to reconfigure the robot, and back up first.

Exit with a cold start

When your task is done, press [FCTN] and select "1 START (COLD)". The controller performs a cold start and comes up ready to operate.

Verify normal operation resumes

Confirm the robot boots to the normal UTILITIES screen and programs are accessible. Check that the setting you changed took effect and that mastering and frames read as expected.

What can go wrong: "3 Controlled start" will not select

Free FROM is below 600 KB, so the configuration menu blocks the option. Check free FROM in the memory status menu and clear unnecessary files from the FR: or FRA: device, then reboot into the configuration menu.

What can go wrong: the robot will not jog in controlled start

This is expected behavior. The controlled start menu is a simple system that cannot move the robot, so finish your setup, then cold start with [FCTN] and "1 START (COLD)" to operate.

What can go wrong: a variable change seems ignored

Some system variables apply only after a restart. Set the variable, power cycle the controller, enter controlled start a second time, then cold start so the new value takes effect.

What can go wrong: confusing controlled start with initial start

Initial start (INIT start from the BOOT MONITOR, reached by holding F1 and F5 at power-on) erases every program, all settings, and the factory mastering data. Controlled start changes none of that on its own, so if a screen offers to reset or initialize, stop and confirm you are not triggering an initial start.

Caution: An accidental initial start erases mastering; correct the cause, restore from backup, and route mastering recovery to a qualified technician.