Adding a thermocouple extension to RAMBo 1.2

[Richard Davies]

Hi Guys,

New member here with a question about thermocouples

I've got a Mendlemax 2.0 with RAMBo 1.2 and Marlin.

I got the thermocouple board v1.0 wired with a type K thermocouple, but I'm struggling to get it connected/setup. 

I'm using the analogue extension pins to connect + to pin1(vcc) gnd to pin2 and signal to pin 7(PKO) and then I remove the existing thermistor from the T0 connection.

In Marlin Config H is normally

#define TEMP_SENSOR_0 5

#define TEMP_SENSOR_1 -1

#define TEMP_SENSOR_2 0

#define TEMP_SENSOR_BED 60

and I changed it to 

#define TEMP_SENSOR_0 -1

#define TEMP_SENSOR_1 0

#define TEMP_SENSOR_2 0

#define TEMP_SENSOR_BED 60

But when I power up and connect Pronterface I get a temperature error.

Has anyone already upgraded to the Thermocouple and successfully configured hard/software and is willing to talk me through it?

Thanks,

Rich

[b Metz]

You need to change pins.h to point to the right pins.

That said the 1.0 thermocouple design does not wrk with Marlin. There is some bad code in it. There is a Ultimaker fork, but it's simpler to use a industrial temp controller.

Spent several months full time messing with it.

[Richard Davies]

Just a quick update, I have this working now and can get the hot end up to 400°C in a couple of minutes.

Thanks to this post http://forum.seemecnc.com/viewtopic.php?f=37&t=4542 I found the right pin assignment to use the thermocouple extension.

Regards,

Rich 

[B]

It does work, but temp readings will be inaccurate when the extruder starts working.  Watch your temp graph, and hit the extrude button... It will look like a earthquake seismograph.

Flaw in Marlin.

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[Richard Davies]

I'm not experiencing this problem with the temperature reading when extruding. Maybe the version of Marlin I have downloaded has been fixed?

Rich

[Alex Nguyen]

Sorry to revive a month old topic but I'm having a similar issue with the exact same setup (MM2.0, RAMBo 1.2, thermo board v1.0).  I'm using the firmware downloaded from Makerstoolworks for mechanical endstops and E3D

Before I finished my post I also figured how to setup the thermocouple.  I'll just post what I did to other unfortunate souls stuck in the same position.  I also don't have a background in EE so please excuse my terminology.  Looking at the RAMBo 1.2e with the USB to the left and motor connections down, I used the analog extension pins directly left of thermistor_0. 

1 - Hardware Connections:  Pins 1 and 2 are the +5V and ground respectively (pin 1 - bottom left; pin 2 - top left) which were connected to the thermocouple board.  The board output was connected to the lower rightmost pin (pin 7 on connector but is Analog Pin 8)

2 - editing pins.h:  line 1965 change from #define TEMP_0_PIN 0 to #define TEMP_0_PIN 8

3 - editing configuration.h:  line 124 change from #define TEMP_SENSOR_0 5 to #define TEMP_SENSOR_0 -1

The key here was that I noticed configuration.h - #define MOTHERBOARD 301.  By searching 301 in pins.h, I was able to change the correct line.  I have the same experience that the temperature signal is quite stable and responds well to small changes in temperature (i.e. holding the hotend in my hand).  I have yet to try heating it yet but the temperature reading works!  Jubilations.

[B Metz]

I used same settings with Marlin... Works great... Until I extrude...  Then the temp graph looks like a seismograph.  I know to isn't fluctuating that much. One of the Marlin developers told me awhile back that the thermocouple code is really bad. 

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[misha kriukow]

Hi Alex,

I've followed your advice and managed to successfully plug in 1 thermocouple. However, I have 2, any suggestions where to plug in the second one? I can't find any schematics or pin numbering anywhere online.

[Alex Nguyen]

Misha,

It's been quite a while since I've looked at the topic but I would imagine using another analog extension pin(e.g. Analog-Ext 7), declaring that pin for your device (e.g. TEMP_1_PIN 7), then telling the board that it's using a thermocouple (e.g. TEMP_SENSOR_1 -1).  Don't take my word for it since I'm not 100% sure.  I found the pins on this page: http://reprap.org/wiki/Rambo_development#Pins

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Alex Nguyen
Graduate Student
UNC/NCSU Joint Department of Biomedical Engineering
North Carolina State University
E-mail: alexng...@gmail.com | akng...@ncsu.edu

[misha kriukow]

hi, thanks it worked. For those interested:

-i plugged in 5v and ground of both thermocouples to pin 1 and 2 respectively (in parallel). The signal of thermocouple 1 to pin 4 and signal of thermocouple 2 to pin 6. In pins.h i changed TEMP_0_PIN to 3 and TEMP_1_PIN to 4.