Temperature offset?

[Queevix]

So, it seems I have a slight offset on my hotend thermistor (a PT1000).
At room temperature (16°C), it shows as being -15°C.
When I heat up to 160°C, the PLA seems to flow nicely, though I have no way to check the actual temperature. I have an IR thermometer, but that seems to not work very well here...

This is the script I use for the relevant heater:
M308 S1 P"temp1" Y"pt1000" B4725 C7.060000e-8 ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1 ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 R1.350 K0.244:0.000 D5.89 E1.35 S1.00 B0 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S280 ; set temperature limit for heater 1 to 280C

It was fine yesterday, and I changed nothing in the meantime.
How could this be solved?

[DIY-O-Sphere]

@Queevix
https://docs.duet3d.com/User_manual/Connecting_hardware/Temperature_connecting_thermistors_PT1000
For the PT1000 B and C parameter are not required. Remove them....

[Queevix]

@DIY-O-Sphere
Thank you for your reply, I removed the B and C parameters, must have been a relic from the previous setup of this printer.

The problem seems to persist though, I'm now at -9°C, and still going down...

[DIY-O-Sphere]

@Queevix
Are you shure that it is an PT1000 sensor?

[Queevix]

@DIY-O-Sphere
I am. I just double checked. I do have a spare, that I could replace it with, but I feel a little awkward about disassembling the hotend if I can't accurately control the temperature.

[DIY-O-Sphere]

@Queevix
If you can reach the connector on the board, you can disconnect the sensor and measure the resistance directly with an ohmmeter.
At 20°C you should measure about 1077Ohm.
You can also do this with the replacement.

[Queevix]

@DIY-O-Sphere
The spare measures 1.070 Kohm at about 18°C, the problematic PT1000 gives me 1.069 Kohm. I feel like this difference would be tolerable, or am I wrong?

[achrn]

@Queevix https://www.sterlingsensors.co.uk/pt1000-resistance-table

1069 is just under 18C, so no you're not wrong.

[Queevix]

@achrn @DIY-O-Sphere
So why am I still getting a reading of -12.4°C in DWC?

[achrn]

@Queevix I have no idea, because the direction it's going implies the resistance the Duet is seeing is slightly lower than what you're measuring - if it was a poor connection I'd expect it to be increasing resistance, which would show as a too high reading, and if it was a short you'd see a reading that's miles off. I don't know what manifests as a slightly too low reading.

[infiniteloop]

@Queevix

So why am I still getting a reading of -12.4°C in DWC?

Does that change if you heat the sensor with a something like hair dryer?

[Queevix]

@infiniteloop
It sure does, it also changes if I set the hotend to any temperature.
The problem (I assume) is that the reading I get from my sensor is about 30 degrees lower than the temperature it's actually at.
so if I heat it up to 160degrees, it would actually be about 190°C

[infiniteloop]

@Queevix

It sure does, it also changes if I set the hotend to any temperature.

So I assume the PT1000 to be working properly.

the reading I get from my sensor is about 30 degrees lower than the temperature it's actually at

For a PT1000, such an offset is uncommon. Maybe you got some parasitic resistance along the lines and/or connectors? As you have a second PT1000, try to connect that directly to the board: does it tell the same readings at room temperature as the one you've built-in?

[Phaedrux]

Can you post your full config.g and config-override.g?
Also post the results of M122 and M98 P"config.g"

[Queevix]

@infiniteloop
The spare gives me more or less the same result (difference of about half a degree), also with the other connector lead.

[Queevix]

@Phaedrux

Here's my full config file. I do not seem to have a config-override on this printer. Could that be a problem?

; Configuration file for Duet 3 Mini 5+ (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Sat Jan 22 2022 15:24:14 GMT+0100 (Central European Standard Time)
 
; General preferences
M575 P1 S1 B57600                            ; enable support for PanelDue
G90                                          ; send absolute coordinates...
M83                                          ; ...but relative extruder moves
M550 P"BigBitch"                             ; set printer name
 
; Network
M552 S1                                      ; enable network
M586 P0 S1                                   ; enable HTTP
M586 P1 S0                                   ; disable FTP
M586 P2 S0                                   ; disable Telnet
 
; Drives
M569 P0.0 S1                                 ; physical drive 0.0 goes forwards
M569 P0.1 S0                                 ; physical drive 0.1 goes forwards
M569 P0.2 S1                                 ; physical drive 0.2 goes forwards
M569 P0.3 S1                                 ; physical drive 0.3 goes forwards
M584 X0.0 Y0.1 Z0.2 E0.3                     ; set drive mapping
M350 X16 Y16 Z16 E16 I1                      ; configure microstepping with interpolation
M92 X80.00 Y80.00 Z400.00 E409.00            ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00          ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00      ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00          ; set accelerations (mm/s^2)
M906 X800 Y800 Z800 E800 I30                 ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                      ; Set idle timeout
 
; Axis Limits
M208 X0 Y0 Z0 S1                             ; set axis minima
M208 X475 Y465 Z450 S0                       ; set axis maxima
 
; Endstops
M574 X1 S1 P"io5.in"                         ; configure switch-type (e.g. microswitch) endstop for low end on X via pin io5.in
M574 Y1 S1 P"io6.in"                         ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin io6.in
M574 Z1 S2                                   ; configure Z-probe endstop for low end on Z
 
; Z-Probe
M950 S0 C"io2.out" 							 ; Duet 3 Mini 5+
M558 P9 C"io2.in" H10 F120 T6000 A3          ; set Z probe type to modulated and the dive height + speeds
G31 P1000 X-39 Y2 Z3.1 S21 H2 T0.02          ; Nozzle offset - Powder Coated Sheet with temperature compensation (0.02mm/°C)
M574 Z1 S2                          		 ; set Z probe trigger value, offset and trigger height
M557 X5:435 Y5:465 P10:10                   ; define mesh grid
M376 H5										 ; Fade height 5mm
 
; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0                           ; create bed heater output on out0 and map it to sensor 0
M307 H0 B0 R0.213 C666.6 D8.13 S1.00 V24.1                            ; 
M140 H0                                      ; map heated bed to heater 0
M143 H0 S80                                  ; set temperature limit for heater 0 to 80C
M308 S1 P"temp1" Y"pt1000"   ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1                           ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 R1.350 K0.244:0.000 D5.89 E1.35 S1.00 B0                            ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                 ; set temperature limit for heater 1 to 280C
 
; Fans
M950 F0 C"out3" Q500                         ; create fan 0 on pin out3 and set its frequency
M106 P0 S0 H-1                               ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"out4" Q500                         ; create fan 1 on pin out4 and set its frequency
M106 P1 S1 H1 T45                            ; set fan 1 value. Thermostatic control is turned on
 
; Tools
M563 P0 D0 H1 F0                             ; define tool 0
G10 P0 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P0 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P1 D0 H1 F0                             ; define tool 0
G10 P1 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P1 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P2 D0 H1 F0                             ; define tool 0
G10 P2 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P2 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P3 D0 H1 F0                             ; define tool 0
G10 P3 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P3 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P4 D0 H1 F0                             ; define tool 0
G10 P4 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P4 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P5 D0 H1 F0                             ; define tool 0
G10 P5 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P5 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P6 D0 H1 F0                             ; define tool 0
G10 P6 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P6 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
 
M563 P7 D0 H1 F0                             ; define tool 0
G10 P7 X0 Y0 Z0                              ; set tool 0 axis offsets
G10 P7 R0 S0                                 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.06
; Custom settings are not defined
 
 

[Queevix]

@Phaedrux

M122

M122
=== Diagnostics ===
RepRapFirmware for Duet 3 Mini 5+ version 3.4.1 (2022-06-01 21:06:56) running on Duet 3 Mini5plus WiFi (standalone mode)
Board ID: URV2B-M396U-D65J0-40KMY-1H03Z-72JMX
Used output buffers: 3 of 40 (27 max)
=== RTOS ===
Static ram: 103684
Dynamic ram: 111512 of which 0 recycled
Never used RAM 26516, free system stack 196 words
Tasks: NETWORK(ready,14.4%,253) HEAT(notifyWait,0.0%,358) Move(notifyWait,0.0%,363) CanReceiv(notifyWait,0.0%,942) CanSender(notifyWait,0.0%,372) CanClock(delaying,0.0%,339) TMC(notifyWait,0.7%,114) MAIN(running,84.0%,426) IDLE(ready,0.1%,29) AIN(delaying,0.8%,273), total 100.0%
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 00:05:29 ago, cause: power up
Last software reset at 2023-02-26 13:21, reason: User, GCodes spinning, available RAM 23252, slot 0
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x00000000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
Aux0 errors 0,0,0
MCU revision 3, ADC conversions started 330081, completed 330080, timed out 0, errs 0
Step timer max interval 1490
MCU temperature: min 23.5, current 28.0, max 28.0
Supply voltage: min 24.0, current 24.1, max 24.1, under voltage events: 0, over voltage events: 0, power good: yes
Heap OK, handles allocated/used 0/0, heap memory allocated/used/recyclable 0/0/0, gc cycles 0
Events: 0 queued, 0 completed
Driver 0: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 17318, writes 9, timeouts 0, DMA errors 0, CC errors 0
Driver 1: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 17317, writes 9, timeouts 0, DMA errors 0, CC errors 0
Driver 2: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 17317, writes 9, timeouts 0, DMA errors 0, CC errors 0
Driver 3: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 17317, writes 9, timeouts 0, DMA errors 0, CC errors 0
Driver 4: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 17318, writes 9, timeouts 0, DMA errors 0, CC errors 0
Driver 5: not present
Driver 6: not present
Date/time: 2023-02-27 07:12:12
Cache data hit count 636420885
Slowest loop: 33.38ms; fastest: 0.13ms
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 22.5MBytes/sec
SD card longest read time 1.5ms, write time 8.5ms, max retries 0
=== Move ===
DMs created 83, segments created 0, maxWait 0ms, bed compensation in use: none, comp offset 0.000
=== MainDDARing ===
Scheduled moves 0, completed 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== AuxDDARing ===
Scheduled moves 0, completed 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
=== GCodes ===
Segments left: 0
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
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
SBC is idle in state(s) 0
Daemon is idle in state(s) 0
Aux2 is idle in state(s) 0
Autopause is idle in state(s) 0
Code queue is empty
=== CAN ===
Messages queued 2964, received 0, lost 0, boc 0
Longest wait 0ms for reply type 0, peak Tx sync delay 0, free buffers 18 (min 18), ts 1648/0/0
Tx timeouts 0,0,1647,0,0,1315 last cancelled message type 4514 dest 127
=== Network ===
Slowest loop: 33.48ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0), 0 sessions
HTTP sessions: 1 of 8
- WiFi -
Network state is active
WiFi module is connected to access point 
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.26
WiFi MAC address d8:bf:c0:15:0b:d5
WiFi Vcc 3.38, reset reason Power up
WiFi flash size 2097152, free heap 25464
WiFi IP address 192.168.1.33
WiFi signal strength -70dBm, mode 802.11n, reconnections 0, sleep mode modem
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

[Queevix]

@Phaedrux

M98 P"config.g"

M98 P"config.g"
HTTP is enabled on port 80
FTP is disabled
TELNET is disabled
Warning: Temperature coefficients ignored due to invalid sensor number 2

[achrn]

@Queevix said in Temperature offset?:

Warning: Temperature coefficients ignored due to invalid sensor number 2

That warning is because you've put temperature compensation using sensor 2 in the probe definition, but you don't have a sensor 2. I don't think it's relevant to the fault under discussion though.

The warning would go if you took the S21 H2 T0.02 out of your G31 line.

[Queevix]

@achrn

I'll try that this evening. Thanks!