Layer shift and M122 Questions

[Cactacae]

I've had a couple prints fail with what appears (with my limited knowledge) to be layer shift and/or extrusion problems.
Haven't eliminated the possibility that a cable isn't binding, and I wasn't around to see it go wrong, but was reviewing the output of M122 after the fact.

Was curious what LaErrors refers to?

M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 2.01(RTOS) running on Duet WiFi 1.02 or later
Board ID: 08DGM-956GU-DJMSJ-6J9D0-3S86J-KBPHG
Used output buffers: 3 of 20 (11 max)
=== RTOS ===
Static ram: 28476
Dynamic ram: 96248 of which 0 recycled
Exception stack ram used: 468
Never used ram: 5880
Tasks: NETWORK(ready,328) HEAT(blocked,1248) MAIN(running,3484)
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 10:12:56 ago, cause: power up
Last software reset time unknown, reason: User, spinning module GCodes, available RAM 6044 bytes (slot 1)
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0041f000 BFAR 0xe000ed38 SP 0xffffffff Task 0x4e49414d
Error status: 16
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 429.5ms, max retries 0
MCU temperature: min 39.2, current 45.7, max 52.9
Supply voltage: min 24.1, current 24.5, max 24.9, under voltage events: 0, over voltage events: 0
Driver 0: standstill, SG min/max 0/199
Driver 1: standstill, SG min/max 0/177
Driver 2: standstill, SG min/max 0/203
Driver 3: standstill, SG min/max 0/1023
Driver 4: standstill, SG min/max not available
Date/time: 2018-08-12 09:24:04
Slowest loop: 114.34ms; fastest: 0.07ms
=== Move ===
Hiccups: 0, StepErrors: 0, LaErrors: 2, FreeDm: 240, MinFreeDm: 150, MaxWait: 150265ms, Underruns: 0, 0
Scheduled moves: 0, completed moves: 0
Bed compensation in use: none
Bed probe heights: 0.000 0.000 0.000 0.000 0.000
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
Heater 0 is on, I-accum = 0.3
Heater 1 is on, I-accum = 0.7
=== GCodes ===
Segments left: 0
Stack records: 2 allocated, 0 in use
Movement lock held by null
http is idle in state(s) 0
telnet is idle in state(s) 0
file is idle in state(s) 0
serial is idle in state(s) 0
aux is idle in state(s) 0
daemon is idle in state(s) 0
queue is idle in state(s) 0
autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Slowest loop: 431.43ms; fastest: 0.01ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
HTTP sessions: 1 of 8

• WiFi -
  Network state is running
  WiFi module is connected to access point
  Failed messages: pending 0, notready 0, noresp 0
  WiFi firmware version 1.21
  WiFi MAC address 5c:cf:7f:76:73:57
  WiFi Vcc 3.34, reset reason Turned on by main processor
  WiFi flash size 4194304, free heap 15376
  WiFi IP address 192.168.1.30
  WiFi signal strength -52dBm, reconnections 0, sleep mode modem
  Socket states: 0 0 0 0 0 0 0 0
  === Expansion ===

Thanks!

Walter...

[dc42]

LaErrors occur when the lookahead algorithm gets an unexpected result. There are 4 different places they can occur and it would be useful to know which one is happening. If you can have PC or laptop running YAT or Pronterface connected via USB during a print, and you send M111 S1 P4 to enable Move debug, then it will print a diagnostic message every time it records a lookahead error.

[Cactacae]

@dc42 Thanks for the info. I'll keep an eye out for LaErrors and will start capturing Move debugs if they reoccur.