What causes FANUC alarm 001?

Part program contains an illegal or malformed command related to the alarm condition. Missing required address word or parameter value in the program block. Programmed value is out of the allowable range. Conflict between active modal codes and the commanded function. Post-processor configuration mismatch for this Fanuc series.

How do I fix FANUC alarm 001?

1. Note the block number shown in the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual. 3. Check for missing words, incorrect values, or conflicting G-code combinations. 4. Verify the program is post-processed for the correct Fanuc series. 5. Correct the program and dry-run at low speed before resuming machining.

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FANUC Controller

Program/G-code · Basic · 15-30 minutes

Alarm 001

Fanuc Alarm 001 - TH Parity Error

Fanuc Alarm 001 TH Parity Error indicates a parity mismatch in serial communication data received through RS-232C interface or network connection. This is typically caused by incorrect communication parameter settings (parity, baud rate, stop bits) between the CNC and external device, damaged RS-232 cable/connector, or electrical noise interference on the communication line.

FANUCProgram/G-codeBasic15-30 minutes

001

Fanuc Alarm 001 - TH Parity Error

TH Parity Alarm

Root Cause Summary

Fanuc Alarm 001 TH Parity Error indicates a parity mismatch in serial communication data received through RS-232C interface or network connection. This is typically caused by incorrect communication parameter settings (parity, baud rate, stop bits) between the CNC and external device, damaged RS-232 cable/connector, or electrical noise interference on the communication line.

Safety

Program data may be corrupted

Causes and Fixes

1
Navigate to SYSTEM > PARAM > press [0] then [SEARCH] to access parameter search. Check Parameter 0020 (I/O channel selection) to confirm which channel is active (0=RS-232, 4=Ethernet).
2
Check Parameters 0100-0103 for RS-232C settings: P0100 (stop bit), P0101 (data bit length, typically 8), P0102 (parity: 0=none, 1=odd, 2=even), P0103 (baud rate: 0=4800, 4=9600, 6=19200). Record current values.
Parameter write enable (P0000 bit 0=1) must be set to modify these parameters. Changes require CNC restart to take effect.
3
Verify external device communication settings match CNC parameters exactly. Most common setting is 9600 baud, 8 data bits, 1 stop bit, Even parity (9600-8-E-1).
4
If mismatch found, correct either CNC parameters or external device settings to match. Set P0000.0=1, modify communication parameters, set P0000.0=0, then power cycle CNC and retry communication.

DIY Feasiblehigh confidence

Call a technician if:

·Hardware interface replacement required
·Persistent errors after parameter verification
·I/O board diagnostic failures

Prevention

Regularly verify communication parameters match external devices
Use proper cable shielding in electrically noisy environments
Implement regular memory card formatting schedule
Monitor buffer usage during large program transfers

Common Mistakes

Ignoring parity bit settings in P0102
Using incorrect cable pinouts for RS-232
Transferring binary files instead of ASCII text
Setting baud rates too high for cable length

Related Alarms

002 003 086 087

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