What causes FANUC alarm PS087?

Part program contains an illegal or incorrectly formatted command for this alarm type. Missing required address word or parameter value in the program block. Programmed value is outside the allowable range for this function. Conflict between the commanded function and the current modal state. Program post-processor not configured correctly for this Fanuc series.

How do I fix FANUC alarm PS087?

1. Note the block number from the Fanuc alarm screen and locate it in the program. 2. Review the command in that block against the Fanuc programming manual for alarm PS087. 3. Check for missing address words, incorrect values, or conflicting G-code combinations. 4. Verify any required machine options are enabled if using advanced functions. 5. Correct the program and verify before resuming machining.

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FANUC Controller

Communication · Intermediate · 15-45 minutes

Alarm PS087

Fanuc Alarm PS087 - Communication Buffer Overflow

PS087 Communication Buffer Overflow occurs when the CNC's communication buffer receives data at a rate exceeding its processing capacity, causing buffer saturation. This is typically caused by excessive DNC/network transmission speeds, inadequate buffer parameter settings, or hardware communication interface issues on the CNC control board.

FANUCCommunicationIntermediate15-45 minutes

PS087

Fanuc Alarm PS087 - Communication Buffer Overflow

BUFFER OVERFLOW

Root Cause Summary

PS087 Communication Buffer Overflow occurs when the CNC's communication buffer receives data at a rate exceeding its processing capacity, causing buffer saturation. This is typically caused by excessive DNC/network transmission speeds, inadequate buffer parameter settings, or hardware communication interface issues on the CNC control board.

Safety

Data may be lost

Causes and Fixes

1
Navigate to SYSTEM > PARAM and check Parameter 20 (Serial communication settings) and Parameter 102 (I/O channel settings). Verify baud rate matches external device settings - typical values are 9600, 19200, or 38400 for RS-232C.
2
Check Parameters 100-104 for buffer allocation settings. For 0i/16i/18i series, verify Parameter 100 bit 0 (I/O buffer expansion). For 30i/31i/32i series, check Parameter 916 and 917 for communication buffer size allocation.
3
Reduce transmission speed from external DNC or CAM software. Enable flow control by setting Parameter 20 bit 5 (RS-232C Xon/Xoff protocol) to 1 or Parameter 20 bit 6 (hardware handshaking) to 1.
4
Clear the communication buffer by pressing RESET while in MDI mode, then restart communication with reduced transmission speed or smaller data packet sizes from host computer.

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