PT100 with amp board  

RE: PT100 with amp board

Grrrr, enough for one day, I'm going out, thought I was losing it.

The thermocouple for measuring the actual temperature was not connecting properly!

Values are within -10 Deg actual at 350 Deg C requested. Will fine tune it a bit more tomorrow.

RE: PT100 with amp board

OK, so I created the E3d amp and thermistor input circuitry in SPICE, used PT100 resistance values from a table to EN 60 751

And got the following results, I had to interpolate values above 800.

The first two columns are from the E3d reference document for the amplifier output.

The Gain 9.998179 is the calculated gain of the amp from reference documentation.

Res is the resistance values from PT100 table to EN 60 751.

VOut.Amp is the calculated V output based on the resistances used from the previous column, which match up with what the E3d documentation says, so so far all good.

Now, V@MCU is the result of using the resistances as shown, in a SPICE simulation of the  E3D Amplifier and thermistor inputs of the Einsy board and is what the chip will see.

Finally ADC is what the internal Analog to Digital conversion will give in the microcontroller.

I put the values into thermistor table 247 in thermistortables.h of the firmware, compiled it, flashed it and tested it and it is almost perfect, a few degrees out at 350 Deg, but this will be component tolerances etc.

If you want to use this table as a more accurate table than the one in firmware, then here is the part you need to copy over the existing values.

{ 0 * OVERSAMPLENR, 0 },
{246 * OVERSAMPLENR, 1 },
{254 * OVERSAMPLENR, 10 },
{262 * OVERSAMPLENR, 20 },
{270 * OVERSAMPLENR, 30 },
{279 * OVERSAMPLENR, 40 },
{287 * OVERSAMPLENR, 50 },
{296 * OVERSAMPLENR, 60 },
{304 * OVERSAMPLENR, 70 },
{312 * OVERSAMPLENR, 80 },
{320 * OVERSAMPLENR, 90 },
{328 * OVERSAMPLENR, 100 },
{336 * OVERSAMPLENR, 110 },
{344 * OVERSAMPLENR, 120 },
{352 * OVERSAMPLENR, 130 },
{360 * OVERSAMPLENR, 140 },
{368 * OVERSAMPLENR, 150 },
{376 * OVERSAMPLENR, 160 },
{384 * OVERSAMPLENR, 170 },
{392 * OVERSAMPLENR, 180 },
{400 * OVERSAMPLENR, 190 },
{408 * OVERSAMPLENR, 200 },
{415 * OVERSAMPLENR, 210 },
{423 * OVERSAMPLENR, 220 },
{431 * OVERSAMPLENR, 230 },
{438 * OVERSAMPLENR, 240 },
{446 * OVERSAMPLENR, 250 },
{453 * OVERSAMPLENR, 260 },
{461 * OVERSAMPLENR, 270 },
{468 * OVERSAMPLENR, 280 },
{476 * OVERSAMPLENR, 290 },
{483 * OVERSAMPLENR, 300 },
{491 * OVERSAMPLENR, 310 },
{498 * OVERSAMPLENR, 320 },
{505 * OVERSAMPLENR, 330 },
{513 * OVERSAMPLENR, 340 },
{520 * OVERSAMPLENR, 350 },
{527 * OVERSAMPLENR, 360 },
{534 * OVERSAMPLENR, 370 },
{541 * OVERSAMPLENR, 380 },
{548 * OVERSAMPLENR, 390 },
{555 * OVERSAMPLENR, 400 },
{624 * OVERSAMPLENR, 500 },
{663 * OVERSAMPLENR, 600 },
{677 * OVERSAMPLENR, 700 },
{687 * OVERSAMPLENR, 800 },
{694 * OVERSAMPLENR, 900 },
{700 * OVERSAMPLENR, 1000 },
{705 * OVERSAMPLENR, 1100 },

RE: PT100 with amp board

If you do decide to use this table, then you may have to check your printing temperatures as they may be different to what you used to use.

My original temperature was always 5 to 6 degrees lower than what it showed on the display, now with the PT100, plus amp and using my table, the temperatures are a lot more accurate, and therefore higher for the same settings.

RE: PT100 with amp board

@chocki

I calibrated the temperature display with this device https://www.timeelectronics.com/decade-boxes/1049-pt100-simulator/ and created a new table (248). Before calibration, the temperatures deviated by approx. 5 degrees from the target value.

RE: PT100 with amp board

@karl-herbert

Do you have your 248 table values so that I can see how they compare to my simulated hardware and calculated values?.

When I compare my values with the original 247 table, it is a lot smoother whereas the original values jumped around a bit.

RE: PT100 with amp board

@chocki

These are the values determined for my printer (Table 248). Deviations from 20 to 500 degrees Celsius according to PT100 Simulator + - 1 degree.

#if (THERMISTORHEATER_0 == 248) || (THERMISTORHEATER_1 == 248) || (THERMISTORHEATER_2 == 248) || (THERMISTORBED == 248) // Pt100 with 4k7 MiniRambo pullup & PT100 Amplifier
const short temptable_248[][2] PROGMEM = {
{007 * OVERSAMPLENR, 0},
{244 * OVERSAMPLENR, 1},
{253 * OVERSAMPLENR, 10},
{261 * OVERSAMPLENR, 20},
{270 * OVERSAMPLENR, 30},
{278 * OVERSAMPLENR, 40},
{287 * OVERSAMPLENR, 50},
{295 * OVERSAMPLENR, 60},
{303 * OVERSAMPLENR, 70},
{311 * OVERSAMPLENR, 80},
{319 * OVERSAMPLENR, 90},
{328 * OVERSAMPLENR, 100},
{334 * OVERSAMPLENR, 110},
{343 * OVERSAMPLENR, 120},
{352 * OVERSAMPLENR, 130},
{359 * OVERSAMPLENR, 140},
{368 * OVERSAMPLENR, 150},
{375 * OVERSAMPLENR, 160},
{383 * OVERSAMPLENR, 170},
{391 * OVERSAMPLENR, 180},
{399 * OVERSAMPLENR, 190},
{407 * OVERSAMPLENR, 200},
{415 * OVERSAMPLENR, 210},
{423 * OVERSAMPLENR, 220},
{432 * OVERSAMPLENR, 230},
{438 * OVERSAMPLENR, 240},
{446 * OVERSAMPLENR, 250},
{454 * OVERSAMPLENR, 260},
{460 * OVERSAMPLENR, 270},
{468 * OVERSAMPLENR, 280},
{476 * OVERSAMPLENR, 290},
{483 * OVERSAMPLENR, 300},
{490 * OVERSAMPLENR, 310},
{498 * OVERSAMPLENR, 320},
{506 * OVERSAMPLENR, 330},
{512 * OVERSAMPLENR, 340},
{520 * OVERSAMPLENR, 350},
{526 * OVERSAMPLENR, 360},
{535 * OVERSAMPLENR, 370},
{541 * OVERSAMPLENR, 380},
{549 * OVERSAMPLENR, 390},
{556 * OVERSAMPLENR, 400},
{626 * OVERSAMPLENR, 500},
};
#endif

RE: PT100 with amp board

.....linearity in an Excel table:

RE: PT100 with amp board

Thanks for that, looks like my simulated perfect tolerance hardware and calculations were pretty much spot on, but I guess when working to 8 decimal places it should be fairly accurate :).

This has now been verified by yourself and corresponds to what I measured with my benchtop meter and thermocouple attached to the heater block.

In both cases, yours and mine, the values are more accurate and linear / smoother than the original table, and it's reassuring to know the hardware is good enough to measure accurately vs theoretical.

RE: PT100 with amp board

Help, please.

I am upgrading the Mk3 to Mk3s and adding Moons .9 to X and Y... and adding PT100...

The PT100 settings in the 0.9 stepper support branch does not compensate for the 4.7 resistor and results in an ambient temperature reading of 1100 C .

or do I have it miss wired or forgot a step in compiling?

thanks.

RE: PT100 with amp board

Nevermind.

I had a bad board.  The Amplifier board was no good.

Carter

RE: PT100 with amp board

Not bad boards... I just can't get them to work properly.

With the  Prusa i3MK3S Moons.9 XY and PT100 and 2 different E3D Amp boards, wiring data to T0 and using table 247 Bunny Science Smooth1

I get 2 different ambient temperature readings.  

Room temperature readout on screen for the pt100/amp are 97 C and 197C   (bed thermistor reads 26C)

How do I rectify the readouts when they should read 27C?

Do I need to make a different table for each Amp board?  How are the tables generated?

RE: PT100 with amp board

@carter-m2

have you made the following changes in the firmware and recompiled it?

Configuration_prusa.h

//#define E3D_PT100_EXTRUDER_WITH_AMP

#define E3D_PT100_EXTRUDER_WITH_AMP

RE: PT100 with amp board

i have created a new table with calibrated values. You may be able to use this one too, but then you have to change the one in the Configuration_prusa.h from 247 to 248 (#define TEMP_SENSOR_0 248):

table 248 add to thermistortables.h:

#if (THERMISTORHEATER_0 == 248) || (THERMISTORHEATER_1 == 248) || (THERMISTORHEATER_2 == 248) || (THERMISTORBED == 248) // Pt100 with 4k7 MiniRambo pullup & PT100 Amplifier

const short temptable_248[][2] PROGMEM = {

{000 * OVERSAMPLENR,    0},          

{239 * OVERSAMPLENR,    1},          

{247 * OVERSAMPLENR,   10},        

{257 * OVERSAMPLENR,   20},        

{265 * OVERSAMPLENR,   30},        

{273 * OVERSAMPLENR,   40},        

{281 * OVERSAMPLENR,   50},        

{289 * OVERSAMPLENR,   60},        

{297 * OVERSAMPLENR,   70},        

{305 * OVERSAMPLENR,   80},        

{313 * OVERSAMPLENR,   90},        

{321 * OVERSAMPLENR,  100},       

{329 * OVERSAMPLENR,  110},       

{339 * OVERSAMPLENR,  120},       

{347 * OVERSAMPLENR,  130},       

{353 * OVERSAMPLENR,  140},       

{361 * OVERSAMPLENR,  150},       

{369 * OVERSAMPLENR,  160},       

{377 * OVERSAMPLENR,  170},       

{385 * OVERSAMPLENR,  180},       

{393 * OVERSAMPLENR,  190},       

{401 * OVERSAMPLENR,  200},       

{409 * OVERSAMPLENR,  210},       

{417 * OVERSAMPLENR,  220},       

{425 * OVERSAMPLENR,  230},       

{431 * OVERSAMPLENR,  240},       

{439 * OVERSAMPLENR,  250},       

{447 * OVERSAMPLENR,  260},       

{453 * OVERSAMPLENR,  270},       

{461 * OVERSAMPLENR,  280},       

{469 * OVERSAMPLENR,  290},       

{475 * OVERSAMPLENR,  300},       

{483 * OVERSAMPLENR,  310},       

{491 * OVERSAMPLENR,  320},       

{499 * OVERSAMPLENR,  330},       

{505 * OVERSAMPLENR,  340},       

{513 * OVERSAMPLENR,  350},       

{519 * OVERSAMPLENR,  360},       

{527 * OVERSAMPLENR,  370},       

{533 * OVERSAMPLENR,  380},       

{541 * OVERSAMPLENR,  390},       

{549 * OVERSAMPLENR,  400},       

{617 * OVERSAMPLENR,  500},       

};

#endif

RE: PT100 with amp board

@carter-m2

Have a look here too -> https://www.reddit.com/r/prusa3d/comments/cnw8dt/how_to_set_up_mk3s_mmu2s_with_pt100/

RE: PT100 with amp board

@karl-herbert

Thanks.  Yes I have things set up based upon the Reddit info and have tried the 248 table.  

With the 248 table...

Right now the temp is reading for 405C instead of 25C (bed readout).  Both Amp boards (strange they are both reading the same value for the first time.  Progress!)

111 ohm at end of thermistor

-1.3 V at Amp board across green and black (middle-data and lower-ground) wires.

5 VDC at red and black wires on Amp (top-5v and lower-ground) wires.

also tried w/o Amp board and got this...jumpy temp readings..

RE: PT100 with amp board

Tried 247 table again...

no change to temp, 405C ???

got error msg.  during sketch upload

Tried upload with Octoprint.  Verified update fine.  Same 405C temp. Table 248

Arduino 1.8.5 (OSX) error message

..........

Arduino: 1.8.5 (Mac OS X), Board: "PrusaResearch Einsy RAMBo"

Sketch uses 227580 bytes (89%) of program storage space. Maximum is 253952 bytes.
Global variables use 6152 bytes of dynamic memory.
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: verification error, first mismatch at byte 0x21300
0x00 != 0x06
avrdude: verification error; content mismatch
avrdude: verification error; content mismatch

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

.....

RE: PT100 with amp board

Success!  Thanks so much!  Table 248 is it!  4:27 am

I screwed up and left the Amp off (#define E3D_PT100_EXTRUDER_NO_AMP)

Once replaced with (#define E3D_PT100_EXTRUDER_WITH_AMP) Everything is correct, very smooth temp control.

link for PT100 Amp SnapCover below....

https://www.prusaprinters.org/prints/30959-e3d-pt100-ampboard-snap-case-and-mount

RE: PT100 with amp board

@carter-m2

Congratulations!
As I described above, this command is very important when using the AMP board:

#define E3D_PT100_EXTRUDER_WITH_AMP

Happy printing 👍 

RE: PT100 with amp board

@carter-m2

Thanks for the link! Also a nice AMP case: https://www.thingiverse.com/thing:2042466

RE: PT100 with amp board

Hi !

My goal is to connect an E3D PT100 temperature sensor to a Prusa MK3S, with an amplifier board. The final objective is to raise the temperature of the extrusion to 350 -400 °C, for special materials.

My research on the internet leads conflicting informations to do this.

Here are my two questions:
1 Where exactly must the 3 pins of the E3D amplifier (0V, signal, + 5V) be connected on the Rambo board?
Apparently it might be in the Ext P3 block of the board, but I don't know which pins exactly. Maybe pin 2 for +5V, pin 4 for 0V and pin 10 for signal ? In this case what happens to the already connected IR sensor? (I wouldn't need IR sensor anymore in my project)

2 Which lines of firmware should I modify?
In the Confirguration_prusa_h tab I found several lines concerning the type of temperature sensor, but several cases are present and I do not know which one to modify.

Thank you very much for your answers