Octoprint communication issues

Taz 6 V3 Dual toolhead. Running latest firmware and Cura. Historically, I could connect to Octoprint\RP3 via Cura and start prints from within Cura with the wireless… Since installing the V3 Dual, the connection isn’t reliable. Every print job the tool head just stops. If i click the “fake acknowledgment” button in Octoprint, the print resumes for a while, then freezes again until I click the “fake acknowledgement” button again.

I’ve tried reflashing my RP3 with a fresh download of Octopi and now I’m running into other connection issues, primarily octoprint is struggling to connect and stay connected to the printer. Below is my serial log, I successfully made a connection and after a couple minutes the connection failed.

Oh and I already replaced the USB cable. No change.

Is this happening to anyone else?

below is my serial log

2018-03-04 20:31:09,833 - Changing monitoring state from ‘Offline’ to ‘Detecting serial port’ 2018-03-04 20:31:09,877 - Serial port list: [’/dev/ttyACM0’] 2018-03-04 20:31:09,878 - Connecting to: /dev/ttyACM0 2018-03-04 20:31:09,886 - Changing monitoring state from ‘Detecting serial port’ to ‘Opening serial port’ 2018-03-04 20:31:09,889 - Connected to: Serial(port=’/dev/ttyACM0’, baudrate=115200, bytesize=8, parity=‘N’, stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor 2018-03-04 20:31:09,891 - Starting baud rate detection 2018-03-04 20:31:09,893 - Changing monitoring state from ‘Opening serial port’ to ‘Detecting baudrate’ 2018-03-04 20:31:09,915 - Trying baudrate: 115200 2018-03-04 20:31:10,034 - Send: N0 M110 N0125 2018-03-04 20:31:19,243 - Recv: �nP<nVH5gJPOn6�HOa�=�Q�h�On}L’�)�mx86b>q^’^�HO!�=|H~�^�a 2018-03-04 20:31:19,314 - Recv: 6�M�w��%�N>p�_x�a�j 2018-03-04 20:31:19,317 - Recv: <��iL6a6g 2018-03-04 20:31:19,325 - Recv: &�=mBoV7d�p|�}� x�J�[�}�M`�YP|"]+X{�Hnl�P<]�8�J�J�(ygJ�J�x��HHvf�J� 2018-03-04 20:31:19,327 - Recv: %� 2018-03-04 20:31:19,330 - Recv: �%�J5HJp|�J��I8%�8�IF�:fh/^7�]�$P< 2018-03-04 20:31:19,332 - Recv: �A�J�a�Jy’ 2018-03-04 20:31:19,350 - Recv: �Z�8z�H�Z�8z�X�:&�^h�F�J�Z�%�%�%f�J�Z�%�H�Z�8%�8��+^>H]�z�KqaK0�.aKK!�NaJ�j��I�AHJ��IF�;]��;]�v�6O6�=�6�V�/m_?y�f~\y�{&~�&��J�z�I�j�J�(�Jo��JHJp|D�Ma 2018-03-04 20:31:19,352 - Recv: 'J�j�I�N�x� 2018-03-04 20:31:19,359 - Recv: MmaY<t_�I�B �]F�J�J�x�:v36l6N&^�J�{�%M�[�jH-H’ 2018-03-04 20:31:35,034 - Recv: jo��J�Z�{�k_�-��J�j�5y~JJ�i�*'�\F];l$P|�~5A��&���&�� 2018-03-04 20:31:45,050 - Baudrate test retry: 4 2018-03-04 20:31:45,054 - Send: N0 M110 N0125 2018-03-04 20:31:45,554 - Baudrate test retry: 3 2018-03-04 20:31:45,558 - Send: N0 M110 N0125 2018-03-04 20:31:46,059 - Baudrate test retry: 2 2018-03-04 20:31:46,062 - Send: N0 M110 N0125 2018-03-04 20:31:46,563 - Baudrate test retry: 1 2018-03-04 20:31:46,567 - Send: N0 M110 N0125 2018-03-04 20:31:47,068 - Baudrate test retry: 0 2018-03-04 20:31:47,071 - Send: N0 M110 N0125 2018-03-04 20:31:47,573 - Trying baudrate: 250000 2018-03-04 20:31:47,577 - Send: N0 M110 N0125 2018-03-04 20:31:47,581 - Recv: echo:Unknown command: “����” 2018-03-04 20:31:47,583 - Recv: ok P15 B3 2018-03-04 20:31:47,588 - Changing monitoring state from ‘Detecting baudrate’ to ‘Operational’ 2018-03-04 20:31:47,595 - Send: N0 M110 N0125 2018-03-04 20:31:47,605 - Recv: ok N0 P15 B3 2018-03-04 20:31:47,607 - Send: N1 M11539 2018-03-04 20:31:47,626 - Recv: echo:Unknown command: “” 2018-03-04 20:31:47,628 - Recv: ok P15 B2 2018-03-04 20:31:47,630 - Send: N2 M2118 2018-03-04 20:31:47,664 - Recv: FIRMWARE_NAME:Marlin FIRMWARE_VERSION:1.1.5.44 EXTRUDER_TYPE:DualExtruder v3 SOURCE_CODE_URL:https://code.alephobjects.com/diffusion/MARLIN PROTOCOL_VERSION:1.0 MACHINE_TYPE:LulzBot TAZ 6 EXTRUDER_COUNT:2 UUID:845f003c-aebd-4e53-a6b9-7d0984fde609 2018-03-04 20:31:47,667 - Recv: Cap:EEPROM:1 2018-03-04 20:31:47,671 - Recv: Cap:AUTOREPORT_TEMP:1 2018-03-04 20:31:47,675 - Recv: Cap:PROGRESS:0 2018-03-04 20:31:47,677 - Recv: Cap:PRINT_JOB:1 2018-03-04 20:31:47,679 - Recv: Cap:AUTOLEVEL:1 2018-03-04 20:31:47,681 - Recv: Cap:Z_PROBE:1 2018-03-04 20:31:47,683 - Recv: Cap:LEVELING_DATA:1 2018-03-04 20:31:47,685 - Recv: Cap:SOFTWARE_POWER:0 2018-03-04 20:31:47,689 - Recv: Cap:TOGGLE_LIGHTS:0 2018-03-04 20:31:47,692 - Recv: Cap:CASE_LIGHT_BRIGHTNESS:0 2018-03-04 20:31:47,694 - Recv: Cap:EMERGENCY_PARSER:1 2018-03-04 20:31:47,696 - Recv: ok N1 P15 B2 2018-03-04 20:31:47,698 - Send: M155 S2 2018-03-04 20:31:47,700 - Recv: echo:SD card ok 2018-03-04 20:31:47,708 - Recv: ok N2 P15 B3 2018-03-04 20:31:47,710 - Send: M20 2018-03-04 20:31:47,712 - Recv: ok P15 B3 2018-03-04 20:31:47,717 - Recv: Begin file list 2018-03-04 20:31:47,756 - Recv: /DOCUME~1/MANUAL/6.01/SOURCE/MANUAL.GLS 7377 2018-03-04 20:31:47,760 - Recv: /DOCUME~1/MANUAL/6.01/SOURCE/MANUAL.GST 363 2018-03-04 20:31:47,806 - Recv: /DOCUME~1/MANUAL/6.01/SOURCE/MANUAL.GLO 7102 2018-03-04 20:31:49,479 - Recv: /PRODUC~1/LABELS/TAZ_60~1.GLA 624898 2018-03-04 20:31:49,485 - Recv: /PRODUC~1/LABELS/TAZ_60~2.GLA 624895 2018-03-04 20:31:49,489 - Recv: /PRODUC~1/LABELS/SERIAL~1.GLA 1741 2018-03-04 20:31:49,492 - Recv: /PRODUC~1/LABELS/TAZ_60~3.GLA 624895 2018-03-04 20:31:49,556 - Recv: /PRODUC~2/JIGS/DOUBLE~1.GCO 3581252 2018-03-04 20:31:49,585 - Recv: /PRODUC~2/JIGS/CONTRO~1/TAZ6_C~1.GCO 3335 2018-03-04 20:31:49,593 - Recv: /PRODUC~2/JIGS/CONTRO~1/TAZ6_C~2.GCO 1389 2018-03-04 20:31:51,559 - Recv: /PRODUC~2/JIGS/CONTRO~1/MARLIN/ARDUIN~1/ARDUIN~3.X/HARDWARE/TOOLS/AVR/SHARE/DOC/GCC-AVR/CHANGE~1.GZ 2717 2018-03-04 20:31:51,572 - Recv: /PRODUC~2/JIGS/CONTRO~1/MARLIN/ARDUIN~1/ARDUIN~3.X/HARDWARE/TOOLS/AVR/SHARE/DOC/BINUTI~1/CHANGE~1.GZ 2174 2018-03-04 20:31:51,794 - Recv: /PRODUC~2/JIGS/CONTRO~1/TAZ6_C~3.GCO 1008 2018-03-04 20:31:51,798 - Recv: /PRODUC~2/JIGS/CONTRO~1/TAZ6_C~4.GCO 1331 2018-03-04 20:31:51,809 - Recv: /PRODUC~2/JIGS/XY_PAR~1.GCO 2219443 2018-03-04 20:32:23,618 - Recv: 2018-03-04 20:34:23,725 - No response from printer after 3 consecutive communication timeouts, considering it dead. Configure long running commands or increase communication timeout if that happens regularly on specific commands or long moves. 2018-03-04 20:34:23,731 - Changing monitoring state from ‘Operational’ to ‘Offline: Too many consecutive timeouts, printer still connected and alive?’ 2018-03-04 20:34:23,736 - Connection closed, closing down monitor

Change Octoprint’s baud rate to fixed at 250000.

Changing the baud to fixed 250000 (as suggested above) will eliminate some connection time since Octoprint won’t have to trial/error to find it.

But the problem you are having (the timeout) doesn’t appear related to baud rate. Octoprint found the correct baud rate (250000), and was operating at that rate.

The log shows a problem while reading the list from the SD card; either a problem with the SD or perhaps a communication error. I would suggest checking the SD card for errors, or try a different SD card, as a first step.

set fixed rate to 250000…new error

Unhandled communication error
There was an unhandled error while talking to the printer. Due to that OctoPrint disconnected. Error: EEPROM CRC mismatch - (stored) 8643 != 55636 (calculated)!

for some reason, continues to receive info from firmware… Weird.

New Log

2018-03-06 06:25:11,946 - Changing monitoring state from ‘Offline’ to ‘Detecting serial port’ 2018-03-06 06:25:12,022 - Serial port list: [’/dev/ttyACM0’] 2018-03-06 06:25:12,024 - Connecting to: /dev/ttyACM0 2018-03-06 06:25:12,027 - Connection closed, closing down monitor 2018-03-06 06:25:12,074 - Changing monitoring state from ‘Detecting serial port’ to ‘Opening serial port’ 2018-03-06 06:25:12,101 - Connected to: Serial(port=’/dev/ttyACM0’, baudrate=250000, bytesize=8, parity=‘N’, stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor 2018-03-06 06:25:12,149 - Changing monitoring state from ‘Opening serial port’ to ‘Connecting’ 2018-03-06 06:25:12,200 - Send: N0 M110 N0125 2018-03-06 06:25:21,386 - Recv: start 2018-03-06 06:25:21,393 - Send: N0 M110 N0125 2018-03-06 06:25:21,395 - Recv: echo:Marlin 1.1.5 2018-03-06 06:25:21,396 - Recv: 2018-03-06 06:25:21,402 - Recv: echo: Last Updated: Nov 21 201713:39:20 | Author: (Aleph Objects Inc., LulzBot Git Repository) 2018-03-06 06:25:21,404 - Recv: echo:Compiled: Nov 21 2017 2018-03-06 06:25:21,407 - Recv: echo: Free Memory: 3166 PlannerBufferBytes: 1264 2018-03-06 06:25:21,484 - Recv: Error:EEPROM CRC mismatch - (stored) 8643 != 55636 (calculated)! 2018-03-06 06:25:21,487 - Changing monitoring state from ‘Connecting’ to 'Error: EEPROM CRC mismatch - (stored) 8643 != 55636 (calculated)! ’ 2018-03-06 06:25:21,495 - Recv: echo:Hardcoded Default Settings Loaded 2018-03-06 06:25:21,498 - Recv: echo: G21 ; Units in mm 2018-03-06 06:25:21,501 - Recv: echo: M149 C ; Units in Celsius 2018-03-06 06:25:21,503 - Recv: 2018-03-06 06:25:21,506 - Recv: echo:Filament settings: Disabled 2018-03-06 06:25:21,508 - Recv: echo: M200 D3.00 2018-03-06 06:25:21,510 - Recv: echo: M200 T1 D3.00 2018-03-06 06:25:21,512 - Recv: echo: M200 D0 2018-03-06 06:25:21,514 - Recv: echo:Steps per unit: 2018-03-06 06:25:21,517 - Recv: echo: M92 X100.50 Y100.50 Z1600.00 2018-03-06 06:25:21,519 - Recv: echo: M92 T0 E760.00 2018-03-06 06:25:21,521 - Recv: M92 T1 E760.00 2018-03-06 06:25:21,543 - Recv: echo:Maximum feedrates (units/s): 2018-03-06 06:25:21,546 - Recv: echo: M203 X300.00 Y300.00 Z3.00 2018-03-06 06:25:21,548 - Recv: echo: M203 T0 E25.00 2018-03-06 06:25:21,550 - Recv: M203 T1 E25.00 2018-03-06 06:25:21,553 - Recv: echo:Maximum Acceleration (units/s2): 2018-03-06 06:25:21,555 - Recv: echo: M201 X9000 Y9000 Z100 2018-03-06 06:25:21,557 - Recv: echo: M201 T0 E10000 2018-03-06 06:25:21,559 - Recv: M201 T1 E10000 2018-03-06 06:25:21,564 - Recv: echo:Acceleration (units/s2): P R T 2018-03-06 06:25:21,586 - Recv: echo: M204 P500.00 R3000.00 T500.00 2018-03-06 06:25:21,593 - Recv: echo:Advanced: S T B X Z E 2018-03-06 06:25:21,597 - Recv: echo: M205 S0.00 T0.00 B20000 X8.00 Y8.00 Z0.40 E10.00 2018-03-06 06:25:21,599 - Recv: echo:Home offset: 2018-03-06 06:25:21,602 - Recv: echo: M206 X0.00 Y0.00 Z0.00 2018-03-06 06:25:21,604 - Recv: echo:Hotend offsets: 2018-03-06 06:25:21,606 - Recv: echo: M218 T1 X0.00 Y0.00 2018-03-06 06:25:21,608 - Recv: echo:Auto Bed Leveling: 2018-03-06 06:25:21,610 - Recv: echo: M420 S0 2018-03-06 06:25:21,613 - Recv: echo:Material heatup parameters: 2018-03-06 06:25:21,615 - Recv: echo: M145 S0 H180 B70 F0 2018-03-06 06:25:21,617 - Recv: M145 S1 H240 B110 F0 2018-03-06 06:25:21,619 - Recv: echo:PID settings: 2018-03-06 06:25:21,622 - Recv: echo: M301 P47.45 I4.83 D116.63 2018-03-06 06:25:21,648 - Recv: echo: M304 P162.00 I17.00 D378.00 2018-03-06 06:25:21,650 - Recv: echo:Z-Probe Offset (mm): 2018-03-06 06:25:21,652 - Recv: echo: M851 Z-1.20 2018-03-06 06:25:29,270 - Recv: echo:SD init fail 2018-03-06 06:25:29,276 - Recv: ok N0 P15 B3

See above post, fixing bad rate wouldn’t allow connect. Reset back to auto (still connected at 250k), pulled SD card and connection remained stable. Will attempt print and post update serial log.

2018-03-06 06:36:09,125 - Changing monitoring state from ‘Offline’ to ‘Detecting serial port’ 2018-03-06 06:36:09,200 - Serial port list: [’/dev/ttyACM0’] 2018-03-06 06:36:09,202 - Connecting to: /dev/ttyACM0 2018-03-06 06:36:09,212 - Changing monitoring state from ‘Detecting serial port’ to ‘Opening serial port’ 2018-03-06 06:36:09,213 - Connection closed, closing down monitor 2018-03-06 06:36:09,217 - Connected to: Serial(port=’/dev/ttyACM0’, baudrate=115200, bytesize=8, parity=‘N’, stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor 2018-03-06 06:36:09,218 - Starting baud rate detection 2018-03-06 06:36:09,219 - Changing monitoring state from ‘Opening serial port’ to ‘Detecting baudrate’ 2018-03-06 06:36:09,243 - Trying baudrate: 115200 2018-03-06 06:36:09,269 - Send: N0 M110 N0125 2018-03-06 06:36:19,275 - Baudrate test retry: 4 2018-03-06 06:36:19,279 - Send: N0 M110 N0125 2018-03-06 06:36:19,780 - Baudrate test retry: 3 2018-03-06 06:36:19,783 - Send: N0 M110 N0125 2018-03-06 06:36:20,283 - Baudrate test retry: 2 2018-03-06 06:36:20,287 - Send: N0 M110 N0125 2018-03-06 06:36:20,786 - Baudrate test retry: 1 2018-03-06 06:36:20,790 - Send: N0 M110 N0125 2018-03-06 06:36:21,290 - Baudrate test retry: 0 2018-03-06 06:36:21,297 - Send: N0 M110 N0125 2018-03-06 06:36:21,799 - Trying baudrate: 250000 2018-03-06 06:36:21,802 - Send: N0 M110 N0125 2018-03-06 06:36:21,805 - Recv: echo:Unknown command: “” 2018-03-06 06:36:21,807 - Recv: ok P15 B3 2018-03-06 06:36:21,811 - Changing monitoring state from ‘Detecting baudrate’ to ‘Operational’ 2018-03-06 06:36:21,819 - Send: N0 M110 N0125 2018-03-06 06:36:21,825 - Recv: ok N0 P15 B3 2018-03-06 06:36:21,831 - Send: N1 M11539 2018-03-06 06:36:21,835 - Recv: echo:Unknown command: “” 2018-03-06 06:36:21,836 - Recv: ok P15 B3 2018-03-06 06:36:21,839 - Send: N2 M2118 2018-03-06 06:36:21,853 - Recv: FIRMWARE_NAME:Marlin FIRMWARE_VERSION:1.1.5.44 EXTRUDER_TYPE:DualExtruder v3 SOURCE_CODE_URL:https://code.alephobjecN2 M21*1iffusion/MARLIN PROTOCOL_VERSION:1.0 MACHINE_TYPE:LulzBot TAZ 6 EXTRUDER_COUNT:2 UUID:845f003c-aebd-4e53-a6b9-7d0984fde609 2018-03-06 06:36:21,857 - Recv: Cap:EEPROM:1 2018-03-06 06:36:21,860 - Recv: Cap:AUTOREPORT_TEMP:1 2018-03-06 06:36:21,864 - Recv: Cap:PROGRESS:0 2018-03-06 06:36:21,866 - Recv: Cap:PRINT_JOB:1 2018-03-06 06:36:21,868 - Recv: Cap:AUTOLEVEL:1 2018-03-06 06:36:21,870 - Recv: Cap:Z_PROBE:1 2018-03-06 06:36:21,874 - Recv: Cap:LEVELING_DATA:1 2018-03-06 06:36:21,877 - Recv: Cap:SOFTWARE_POWER:0 2018-03-06 06:36:21,879 - Recv: Cap:TOGGLE_LIGHTS:0 2018-03-06 06:36:21,884 - Recv: Cap:CASE_LIGHT_BRIGHTNESS:0 2018-03-06 06:36:21,886 - Recv: Cap:EMERGENCY_PARSER:1 2018-03-06 06:36:21,888 - Recv: ok N1 P15 B3 2018-03-06 06:36:21,890 - Send: M155 S2 2018-03-06 06:36:23,956 - Recv: echo:SD init fail 2018-03-06 06:36:23,962 - Recv: ok N2 P15 B3 2018-03-06 06:36:23,974 - Recv: ok P15 B3 2018-03-06 06:36:25,984 - Recv: T:22.91 /0.00 B:29.22 /0.00 T0:22.91 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:27,984 - Recv: T:22.91 /0.00 B:29.22 /0.00 T0:22.91 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:29,981 - Recv: T:22.94 /0.00 B:29.25 /0.00 T0:22.94 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:31,981 - Recv: T:22.97 /0.00 B:29.22 /0.00 T0:22.97 /0.00 T1:22.97 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:33,981 - Recv: T:22.91 /0.00 B:29.25 /0.00 T0:22.91 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:35,982 - Recv: T:22.91 /0.00 B:29.25 /0.00 T0:22.91 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:37,982 - Recv: T:23.06 /0.00 B:29.17 /0.00 T0:23.06 /0.00 T1:22.97 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:39,982 - Recv: T:22.84 /0.00 B:29.25 /0.00 T0:22.84 /0.00 T1:23.09 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:41,981 - Recv: T:23.03 /0.00 B:29.19 /0.00 T0:23.03 /0.00 T1:22.97 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:43,982 - Recv: T:22.94 /0.00 B:29.17 /0.00 T0:22.94 /0.00 T1:23.06 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:45,982 - Recv: T:22.97 /0.00 B:29.25 /0.00 T0:22.97 /0.00 T1:22.97 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:47,982 - Recv: T:22.94 /0.00 B:29.22 /0.00 T0:22.94 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:49,982 - Recv: T:22.97 /0.00 B:29.22 /0.00 T0:22.97 /0.00 T1:22.97 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:51,981 - Recv: T:23.00 /0.00 B:29.19 /0.00 T0:23.00 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:53,983 - Recv: T:22.91 /0.00 B:29.14 /0.00 T0:22.91 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:55,999 - Recv: T:22.81 /0.00 B:29.22 /0.00 T0:22.81 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:57,998 - Recv: T:22.84 /0.00 B:29.17 /0.00 T0:22.84 /0.00 T1:23.06 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:36:59,999 - Recv: T:22.94 /0.00 B:29.22 /0.00 T0:22.94 /0.00 T1:23.03 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:37:02,000 - Recv: T:22.91 /0.00 B:29.08 /0.00 T0:22.91 /0.00 T1:23.06 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:37:03,998 - Recv: T:22.84 /0.00 B:29.08 /0.00 T0:22.84 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:37:05,999 - Recv: T:22.97 /0.00 B:29.11 /0.00 T0:22.97 /0.00 T1:22.94 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:37:08,001 - Recv: T:22.87 /0.00 B:29.08 /0.00 T0:22.87 /0.00 T1:23.00 /0.00 @:0 B@:0 @0:0 @1:0 2018-03-06 06:37:10,000 - 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There is missing data (partial replies) in the last two logs you posted. That, and failure to connect when set at 250k look like a bad cable or bad USB port. Set to 250000 and leave it there - that is the correct setting. Use a short (<2m) usb cable and keep it away from power cords. If you can’t get a reliable connect at 250000, nothing else is going to succeed after that either.

You are using firmware 1.1.5.44. There was a change in 1.1.5.71 that was specifically intended to correct problems with dual extruder (extra temp report data) overflowing the Octoprint buffer. I therefore recommend using 1.1.5.71 (or later) firmware since you have a dual extruder.

Only other thought - IF this happened only with the new tool head (and 1.1.5.71 doesn’t solve it) - is that some component there is bad and causing enough electrical noise to interfere with usb comm. Might be time to ring up Lulzbot support.

Having an SD card plugged in with LOTS of files on it falls into this condition! AKA: It takes TOO LONG to list ALL the files…

Agreed – but until the communication stream is coming through complete (right now, it is missing portions) it is tough to tell if there is an actual timeout condition or not. In his initial log, the M20 was issued at 20:31:47 and responses were flowing fine to 20:31.51 (so just 4 seconds) – then they stopped. So the timeout didn’t occur because file names kept coming through for too long, rather it occurred because there was NOTHING coming through.

It listed for over 30 seconds and then died, but the output of the M20 was truncated. That is why it did not timeout after they unplugged the SD card.

No, to the contrary the log shows file listing only lasted 4 seconds, then abruptly stopped.

The M20 was: Send: M20 2018-03-04 20:31:47,712
The last file response was: 2018-03-04 20:31:51,809 - Recv: /PRODUC~2/JIGS/XY_PAR~1.GCO 2219443

That is only 4 seconds later. The firmware stopped responding right after that. The next messages were "20:32:23,618 - Recv: " (empty or truncated message) and then Octoprint logging the timeout with “2018-03-04 20:34:23,725 - No response from printer…”. The file listing stopped after only 4 seconds. Then a partial message 32 seconds later, then nothing. Either the firmware stopped sending the list, or a communications failure prevented it from being received.

That indicates either a communications failure or an SD card problem. After removing the SD card, there are still missing characters in the received data – which isolates it to a communications issue. The root problem is NOT the Octoprint timeout value.

As much as it might amuse me to try explaining RX buffer size overrun to you it really is not worth it. The data was received just not kept.

That might actually amuse everyone. But which is it, a timeout from a long running M20 command, or a buffer overrun? Make up your mind please.

I understand serial comms and buffering (in general, and specific to Octoprint) just fine, thank you. The kind of buffer overrun you describe does not match what is shown in those logs. Neither does Octoprint’s long command timeout value. Even in the initial connection response, there are missing characters – if there was a buffer overrun problem with the firmware and/or Octoprint there, it would be happening to everyone.

Look at this line, for example:
Recv: FIRMWARE_NAME:Marlin FIRMWARE_VERSION:1.1.5.44 EXTRUDER_TYPE:DualExtruder v3 SOURCE_CODE_URL:https://code.alephobjecN2 M21*1iffusion/MARLIN PROTOCOL_VERSION:1.0 MACHINE_TYPE:LulzBot TAZ 6

I agree that LOOKS like a buffer overrun at first glance – there are certainly characters being lost – but digging deeper it isn’t a simple case of firmware sending too fast / too much for pyserial and Octoprint to process. Octoprint on an Rpi3 has no trouble keeping up with that output, and that output is common to everyone. Something else is causing the character loss – bad cable or port, or interference perhaps.