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Repetier K Type Thermocouple

Posted by Levent 
Repetier K Type Thermocouple
March 21, 2014 01:06AM
Hi I just want to know what's called this thermocouple on repetier config tool. I mean 100k thermistor is epcos100k... so I got k type and I havent seen it there.
Re: Repetier K Type Thermocouple
March 21, 2014 01:36AM
i dont use repetier so im afraid i dont know
Re: Repetier K Type Thermocouple
March 21, 2014 02:09AM
Thank you for repply. I have tested a few types of thermocouples on repetier config tool but all I see 500 degrees or -40/-48 degrees on host.I'm gonna try something else but I have to choose the right model of thermocouple on repetier for k type thermocouple.
Re: Repetier K Type Thermocouple
March 21, 2014 04:05AM

It depnds on what controller board you are using in conjunction with with thermo couple.
Some need a 4.7k pull up some need 1 K

Heres the text from the Marlin config.h i use ....it might help you figure out what you need to do

Good luck

//=============================Thermal Settings ============================
//--NORMAL IS 4.7kohm PULLUP!-- 1kohm pullup can be used on hotend sensor, using correct resistor and table
//// Temperature sensor settings:
// -2 is thermocouple with MAX6675 (only for sensor 0)
// -1 is thermocouple with AD595
// 0 is not used
// 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
// 2 is 200k thermistor - ATC Semitec 204GT-2 (4.7k pullup)
// 3 is mendel-parts thermistor (4.7k pullup)
// 4 is 10k thermistor !! do not use it for a hotend. It gives bad resolution at high temp. !!
// 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan) (4.7k pullup)
// 6 is 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)
// 7 is 100k Honeywell thermistor 135-104LAG-J01 (4.7k pullup)
// 1k ohm pullup tables - This is not normal, you would have to have changed out your 4.7k for 1k
// (but gives greater accuracy and more stable PID)
// 51 is 100k thermistor - EPCOS (1k pullup)
// 52 is 200k thermistor - ATC Semitec 204GT-2 (1k pullup)
// 55 is 100k thermistor - ATC Semitec 104GT-2 (Used in ParCan) (1k pullup)

#define TEMP_SENSOR_0 1
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
Re: Repetier K Type Thermocouple
March 21, 2014 06:34AM
Thanks for reply. I'll look and try this night. As I see I need to change firmware's thermal codes like yours. Thanks.
Re: Repetier K Type Thermocouple
March 21, 2014 06:47AM
the main difference is whether your system is using a 4.7k pull up or a 1 k

The only major difference in the other options is the temp tables because thermisistors are not linear.

You should still get things working using the standard setting ..its just using the correct tables makes in more accurate
Re: Repetier K Type Thermocouple
March 21, 2014 08:23AM
Thanks for reply my friend. Actually when my 100 k thermistor was broken I need tochange it with k type thermocouple on extruder. I'm using repetier and I think I need to select that type on the config tool on repetier website for the firmware but I just dont have any idea what will I choose or which code that I'm going to add or change on firmware.
Re: Repetier K Type Thermocouple
March 22, 2014 12:51AM
A thermocouple works entirely differently from a thermistor; you can't just plug it into the same pins the thermistor used and expect it to work by changing settings in the firmware. The thermocouple needs its own interface chip; the most common ones seem to be the AD595 and the MAX6675. In Repetier firmware you set the sensor type according to the interface chip you have: 100 is the AD595, 101 is the MAX6675, and 102 is the MAX31855. There are a couple of other defines you might have to uncomment in configuration.h as well to enable the code that talks to these chips, and the corresponding TEMPSENSOR_PIN is defined differently.

If you don't have one of those interface chips then you're out of luck. Perhaps your controller board has one built in already; I don't know all the boards that are out there but I know that RAMPS 1.4 (which is what I have) does not. I did get a k type thermocouple (mostly) working in my setup by adding a MAX6675 the other day, but it doesn't work out of the box and it's not obvious how to connect it and configure the firmware. If you have a MAX6675 I can try to help; if you have one of the other interface chips then I have no clue.
Re: Repetier K Type Thermocouple
March 22, 2014 10:08AM
I believe that Levent is using a Megatronics 2.0 board, which includes hardware support for two thermocouple inputs via screw terminal inputs (like the power supply inputs) in addition to the thermistor pins. The thermocouple inputs are analog pin 4 (TC#1) and analog pin 8 (TC#2) if I'm reading the schematics correctly, and the interface chip is an AD597 or an AD-S08.

My guess is that he should pick Analog Pin #4 for the temperature sensor pin and AD595 for the sensor in the Repetier web configuration tool, unless the AD597 reads differently than the AD595.....
Re: Repetier K Type Thermocouple
March 22, 2014 03:23PM
I think the AD597 can be considered equivalent to the 595 for this application, so he should be fine using 100 for the sensor type. (Whether it works is another story, I think the developer for Repetier has stated that he doesn't have any thermocouples so he hasn't debugged the portions of the firmware that deal with them ...)
Re: Repetier K Type Thermocouple
March 22, 2014 04:41PM
Thanks for the replies. That looks more complex than I expect I think. I'll be read your messages and try to connect it with your helpings.
Re: Repetier K Type Thermocouple
March 24, 2014 05:00PM
I got megatronics v2 with repetier firmware. And I have tried your solution but still the same error appears.It says;

22:46:09.903 : extruder 0: temp sensor defect
22:46:09.903 : heated bed: working
22:46:09.906 : Errortongue sticking out smileyrinter set into dry run mode until restart! this. I have used analog pin 4 and AD595 and this message appears. I'm trying to use k type thermocouple. :/
Re: Repetier K Type Thermocouple
March 24, 2014 11:57PM
I don't know enough about your setup to offer much specific advice, but here are a few suggestions:

* Make sure the thermocouple is good. (Measure its resistance with a multimeter. The resistance depends on the length and gauge of the thermocouple wires, but shouldn't be more than a couple of kiloohms.)
* Make sure the thermocouple isn't electrically shorted to any part of your printer. (Measure the resistance from one of the thermocouple wires to the heater block of your hotend, if that's where it's mounted. The resistance should be megaohms at least, and ideally off-the-scale high.)
* Make sure the thermocouple interface IC, AD597, is actually present on your board, I guess? (IC5, right next to the TC input block, according to the documentation I see online)
* Of course, doublecheck your connections and the settings in the firmware.

With the AD597 interface chip you actually have a pretty good chance of getting things working, at least as far as the firmware is concerned. The other TC interface chips have their own A-D converters and communicate with the microcontroller through the SPI port, which needs its own special code in the firmware (and is not as tested as the rest of the firmware and is therefore prone to bugs). The AD597 puts out an analog voltage that the microcontroller can read just like it does the thermistor signals; all that needs to change is the lookup table -- much less opportunity for things to go wrong.
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