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Repetier PID settings and thermistor tables

Posted by miro87043 
Repetier PID settings and thermistor tables
March 30, 2012 09:27PM
Pertinent information: I'm using Repetier firmware, gen 7 electronics, makergear hotend, with honeywell 100k thermistor.

1: I have not been able to successfully add the thermistor table from the wiki to my firmware. I can upload firmware with the needed thermistor table but I get T:0 in pronterface. In the firmware, I added the table to #define USER_THERMISTORTABLE1
I set #define EXT0_TEMPSENSOR_TYPE 6 // 6 corresponds to above
I set #define NUM_TEMPS_USERTHERMISTOR1 20 // I counted 20 sets of numbers in the table
I deleted the first 2 lines in the wiki's table because;
#define NUMTEMPS 20 // is already defined, as shown above
short temptable[NUMTEMPS][2] = // not sure what this is but it won't compile.

Any advice?

2: Using PID on my extruder puts my temps at 2 degrees less than my set Temp. For example if I set my extruder to 180 it stays at 178. This is not a huge problem, but in order to start a print I must over heat the extruder in order to meet the set temp at the beginning of a print. Otherwise the printer waits indefinitely for the extruder to hit the set temp.
I've tried to read up on PID settings, but so far it makes little sense to me.
Any advice on changes to my PID settings?
Re: Repetier PID settings and thermistor tables
March 31, 2012 04:29AM
miro87043 Wrote:
-------------------------------------------------------
> Pertinent information: I'm using Repetier
> firmware, gen 7 electronics, makergear hotend,
> with honeywell 100k thermistor.
>
> 1: I have not been able to successfully add the
> thermistor table from the wiki to my firmware. I

That table is not coorect for the repetier-firmware. You need to multiply the first value with 4 and the second with 8, see Repetier Wiki page for thermistor tables:
https://github.com/repetier/Repetier-Firmware/wiki/Temperature-control
With the original values you will get wrong values.

> can upload firmware with the needed thermistor
> table but I get T:0 in pronterface. In the
> firmware, I added the table to #define
> USER_THERMISTORTABLE1
> I set #define EXT0_TEMPSENSOR_TYPE 6 // 6
> corresponds to above
Correct
> I set #define NUM_TEMPS_USERTHERMISTOR1 20 // I
> counted 20 sets of numbers in the table
> I deleted the first 2 lines in the wiki's table
> because;
> #define NUMTEMPS 20 // is already defined, as
> shown above
> short temptable[2] = // not sure what this is but
> it won't compile.

Thats beacuse the wiki used wasn't meant for repetier firmware. But your replacements look ok.
>
> Any advice?
>
> 2: Using PID on my extruder puts my temps at 2
> degrees less than my set Temp. For example if I
> set my extruder to 180 it stays at 178. This is
> not a huge problem, but in order to start a print
> I must over heat the extruder in order to meet the
> set temp at the beginning of a print. Otherwise
> the printer waits indefinitely for the extruder to
> hit the set temp.
> I've tried to read up on PID settings, but so far
> it makes little sense to me.
> Any advice on changes to my PID settings?

Looks like you need to increase
#define EXT0_PID_INTEGRAL_DRIVE_MAX 130
Thats the highest output pwm setting you think you may need to reach target temperature. So the integral part will never go over this value, which can prevent reaching the target temp. if it is much to low. Max value is 255.

If you are using eeprom, you have to change it there! Best done with Repetier-Host, as it has an eeprom editor included for my firmware.


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Re: Repetier PID settings and thermistor tables
April 01, 2012 11:29AM
Thanks!

I changed to:
#define EXT0_PID_INTEGRAL_DRIVE_MAX 220
This works and I got my thermistor table to work with your advice, but I'm still extruding PLA at 150. I think this is a combination of thermistor variability and needing more insulation on my hotend given the fan blowing at it. smiling smiley

I'll do some more messing around...
Re: Repetier PID settings and thermistor tables
April 01, 2012 12:03PM
I'am extruding PLA with 170°C but I know the sensor is placed at a bad place returning much lower values then inside the extruder. A fan may make it even worse.


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Repetier-Server - the solution to control your printer from everywhere.
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Re: Repetier PID settings and thermistor tables
April 01, 2012 03:22PM
repetier Wrote:
-------------------------------------------------------
> I'am extruding PLA with 170°C but I know the
> sensor is placed at a bad place returning much
> lower values then inside the extruder. A fan may
> make it even worse.

That's what I'm thinking. It doesn't concern me to much. The difficult part was not being able to reach set temp, but you helped me solve that!

Thanks!!!
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