FANUC FANUC CNC Controllers & Human-Machine Interface (HMI) 2 — Questions and Answers
Question 1: Which alarm prefix does FANUC use for errors related to the robot servo drive system?
- SYST
- SRVO (Correct answer)
- INTP
- MOTN
Correct answer: SRVO
SRVO alarms indicate servo drive faults such as overcurrent, encoder errors, or position deviations; SYST covers system errors, INTP covers interpreter errors, and MOTN covers motion planning errors.
Question 2: A FANUC 'SRVO-023 Stop error excess' alarm most likely indicates which condition?
- The teach pendant battery needs replacement
- The robot's position error exceeded the allowed limit during deceleration to a stop (Correct answer)
- A DeviceNet communication timeout occurred
- Program memory is full and needs to be cleared
Correct answer: The robot's position error exceeded the allowed limit during deceleration to a stop
SRVO-023 occurs when the servo system detects that actual position deviated from commanded position beyond the allowable limit during a stop, often due to excessive load or mechanical binding.
Question 3: What is the function of the FANUC system variable $SCR_GRP[1].$AXISMASK?
- Sets the serial communication baud rate for group 1 devices
- Defines which robot axes belong to motion group 1 using a bitmask (Correct answer)
- Configures the screen refresh rate for the HMI display
- Sets the maximum speed limit for all axes in group 1
Correct answer: Defines which robot axes belong to motion group 1 using a bitmask
$SCR_GRP[1].$AXISMASK is a system variable whose bitmask value specifies which physical axes are members of motion group 1, critical for multi-robot or extended-axis configurations.
Question 4: Which FANUC backup method captures programs, system variables, I/O configuration, and mastering data in a single operation?
- MIRROR IMAGE backup
- FILE utility 'All of the Above' backup (Correct answer)
- Cold Start backup procedure
- System DUMP function only
Correct answer: FILE utility 'All of the Above' backup
The FANUC FILE utility's 'All of the Above' option (or equivalent full backup) saves all categories of controller data including programs, variables, I/O setup, and calibration data in one step.
Question 5: What does a FANUC program state of 'PAUSED' indicate?
- The program completed its last line successfully
- Execution stopped mid-program and can be resumed from the current line (Correct answer)
- The controller is waiting for supervisor approval to continue
- The controller entered low-power sleep mode automatically
Correct answer: Execution stopped mid-program and can be resumed from the current line
PAUSED means program execution halted at a specific line (due to an alarm, hold, or operator action) and can be resumed from that exact point, unlike ABORTED which requires restarting from the beginning.
Question 6: How does a FANUC R-30iB controller determine the maximum number of programs that can be stored?
- A fixed limit of exactly 100 programs
- A fixed limit of exactly 999 programs
- Available FROM (Flash ROM) space, allowing thousands of programs depending on size (Correct answer)
- A fixed limit of 256 programs set at the factory
Correct answer: Available FROM (Flash ROM) space, allowing thousands of programs depending on size
Program count is limited by available FROM flash memory space rather than a fixed file count, so thousands of small programs or fewer large programs can be stored depending on their size.
Question 7: Which FANUC feature allows software-defined limits on the robot's allowable Cartesian workspace, independent of physical limit switches?
- Joint hard limits only
- Cartesian soft limits (interference zones / workspace limits) (Correct answer)
- Hardware limit switches only
- Speed override percentage reduction
Correct answer: Cartesian soft limits (interference zones / workspace limits)
FANUC Cartesian soft limits create virtual workspace boundaries enforced by the controller software, restricting robot motion to a defined safe region without requiring additional hardware.
FANUC FANUC CNC Controllers & Human-Machine Interface (HMI) 2
Which alarm prefix does FANUC use for errors related to the robot servo drive system?