cadenrank Posted January 26, 2022 Report Share Posted January 26, 2022 This is a thread I've been lurking on for a while, and just yesterday decided to order some parts to try some things out. My goal is to use it as a way to monitor the thermocouple remotely temporarily, but eventually plan to turn it a full controller as well. My question is that I noticed that the thermocouple amplifiers listed in the original github file say Max31856, and Max31855. I can see the pinouts are different between them. I ordered the 31856 because it was one of the only ones in stock. I read a few times in here about there being differences and issues with using one or the other, and am wondering what is needed differently from the original instructions to utilize the 31856. All of the diagrams I see for it show the pinout for 31855, and while I can gather which ones are the corresponding ones, it seems like maybe there needs to be changes in code or something? Like I said, I don't have any of these parts yet besides the pi and the type K thermocouple. I plan to follow the instructions as they were written (mostly because this is the first of this kind of project I've ever done) but want to know if I'm expecting to change something with the use of the 31856 board. Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 26, 2022 Report Share Posted January 26, 2022 4 hours ago, rondoc said: Interesting I have same setup and I only get 32F and stuck for temperature , even after a reboot. This same with 2 of adafruit boards. I am now starting from scratch...new format on SD CARD. and following Jason completely. I wonder if the GPIO is somehow setup wrong. I tried the GPIO TEST that Jason gives to view all the pins but it didn't run on my raspberry. 3B only the 4. All a bit frustrating almost as bad as learning to throw many moons ago. I have reinstalled rasping an followed Jason's info but still not reading correctly. It is stuck at 32F. It's also not loading from 0.0.0.0:8081. I might have a bad pi so that's my next step. I thought this was going to be easy....problem is with so much of the software it is very hard to trace a failure . On the github info from Jason it says for local use 127.0.0.0:8081 but I have no idea what this gets me as nothing happens .what is supposed to happen ? Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 26, 2022 Report Share Posted January 26, 2022 5 hours ago, cadenrank said: This is a thread I've been lurking on for a while, and just yesterday decided to order some parts to try some things out. My goal is to use it as a way to monitor the thermocouple remotely temporarily, but eventually plan to turn it a full controller as well. My question is that I noticed that the thermocouple amplifiers listed in the original github file say Max31856, and Max31855. I can see the pinouts are different between them. I ordered the 31856 because it was one of the only ones in stock. I read a few times in here about there being differences and issues with using one or the other, and am wondering what is needed differently from the original instructions to utilize the 31856. All of the diagrams I see for it show the pinout for 31855, and while I can gather which ones are the corresponding ones, it seems like maybe there needs to be changes in code or something? Like I said, I don't have any of these parts yet besides the pi and the type K thermocouple. I plan to follow the instructions as they were written (mostly because this is the first of this kind of project I've ever done) but want to know if I'm expecting to change something with the use of the 31856 board. I have the 32856 adafruit breakout boards. The software by Jason does cover the pinout and also uses the 31856 library from adafruit. In theory it should all work. In the config.py file you need to change thermocople to K and also change selection of board , it is 0 for the 56 and 1 for the 55 so you need to reverse those. Also the pinout is specified there being 4 GPIO PINS IN USE. the 3.3 volts from the pi goes to the Vin on the breakout board. Ground to any GND . It all worked when I first set it up and the profile system for heating is very clever...overkill for a pottery kiln as it was designed for a reflow soldering station but should be ok. Now for unknown reasons the temperature reading is screwed up. Not sure why but hopefully will be fixed very soon. I plan to use the system for monitoring until I feel it is solid..don't have that feeling yet! Let us know how it all works for you..together we can succeed. Ron. cadenrank 1 Quote Link to comment Share on other sites More sharing options...
cadenrank Posted January 26, 2022 Report Share Posted January 26, 2022 Oop, I found it. So for the connections from the 32856 to the pi, would be as follows: GPIO 17 (pin 11 on PI) would be connected to the terminal labeled SDO on the adafruit 32856. GPIO 22 (pin 15) would go to SCK GPIO 27 (pin 13) would go to CS GPIO 10 (pin 19) would go to SDI and then a ground to GND? and then like you said, switching the 1 and 0 in config.py, and changing the thermocouple type. Correct me if that's wrong, or if I'm understanding incorrectly. Thanks again. Quote Link to comment Share on other sites More sharing options...
silfrsmithr Posted January 26, 2022 Report Share Posted January 26, 2022 I got rid of the breakout board and wired directly pin to pin. Same results. I think I I'm going to have to wait for my '55 thermocouple interface to get here before I spend any more time on this. When I get that board in, I'll set the whole system back up but for that board and I'll post my results back here. Once again, my thanks to any and all who have contributed on this project, and especially those who have helped me directly. Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 27, 2022 Report Share Posted January 27, 2022 12 hours ago, silfrsmithr said: I got rid of the breakout board and wired directly pin to pin. Same results. I think I I'm going to have to wait for my '55 thermocouple interface to get here before I spend any more time on this. When I get that board in, I'll set the whole system back up but for that board and I'll post my results back here. Once again, my thanks to any and all who have contributed on this project, and especially those who have helped me directly. I think changing to the 55 chip makes sense. I will keep trying with the adafruit breakout board..funny it show correct temp for a second before going back to 32F. I'd love to know why this is happening. Ron. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 27, 2022 Report Share Posted January 27, 2022 (edited) 3 hours ago, rondoc said: funny it show correct temp for a second before going back to 32F. I'd love to know why this is happening. Just an idea which might spark some thought, for K type tcouples 32 degrees is zero volts, 100 degrees is about 4 mv. You might want to check actual output with a voltmeter and / or check polarity as thermocouples can be marked opposite from a perception standpoint and that chip may not include negative temperatures in its range. All else fails you should be able to test the chip by applying a few millivolts and checking it’s displayed output against a table. K type table https://www.pyromation.com/downloads/data/emfk_f.pdf Edited January 27, 2022 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 27, 2022 Report Share Posted January 27, 2022 On 1/25/2022 at 7:25 AM, newps said: Hi Ken, My first thoughts are that the issue is really due to the Max31856 controller not getting set up by the program properly. but that will depend if you have the Adafruit_GPIO module installed and it was working. I can't get it on a totally new build SD card as that module is deprecated. My other thoughts are that as you are using a K type thermocouple the Max31855 tc amplifier would be better, mainly because I believe many more of the kiln-controller users are using the K-type and max31855 set up and the problems with it have been resolved. I have to use the 31856 because I am stuck with a S type thermocouple in my kiln. It is an interesting thought to use this program for lost wax casting of silver, I would be interested to know more of how you do it. my experience was a small domestic oven to melt the wax out and then heating the casting flask with a blowtorch before pouring the molten silver into it. You can buy a MAX31855 for any kind of thermocouple and swap out the type K chip. I did this and also made a PCB to try making my own boards. The MAX31856 is good because it doesn't need a different chip for each type of thermocouple. It shouldn't be to difficult to get the software working with 31856, one day I might buy a board and take a look. cadenrank 1 Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 28, 2022 Report Share Posted January 28, 2022 On 11/28/2018 at 12:13 PM, jbruce said: I got tired with going down to the basement to make sure my kiln was working properly and running on schedule so I started (forked) a project to control my KS-1018 using a raspberry pi. With this I can: monitor my kiln from anywhere using any device that has a web browser (phone/tablet/computer) easily create new schedules, edit existing schedules, including infinite ramps & soaks accurate PID control get schedule cost estimates and actuals If anyone is interested, here is the github link... https://github.com/jbruce12000/kiln-controller The cost for everything I bought was under $200.00, but my time investment has been high. Again, this is for geeks that were born with a soldering iron in one hand. I have followed instruction on github site and it works until I get this "ERROR oven : problem reading temp N/C etc etc..implying I have lost the maximum adafruit module and it hasn't changed. However until I get to this in terminal. I readout temp fine after 0.0.0.0.:8081..the TC is fine and checked by a Fluke all the time. This is repeatable. Help please. Quote Link to comment Share on other sites More sharing options...
MarkTilles Posted January 28, 2022 Report Share Posted January 28, 2022 (edited) 13 minutes ago, rondoc said: I have followed instruction on github site and it works until I get this "ERROR oven : problem reading temp N/C etc etc..implying I have lost the maximum adafruit module and it hasn't changed. However until I get to this in terminal. I readout temp fine after 0.0.0.0.:8081..the TC is fine and checked by a Fluke all the time. This is repeatable. Help please. Rondoc, i have a working ISO image of 7.5 GB card I can share with you on MS OneDrive. It’s set up with a Pi zero w and max31856 if you might want to give it a whirl? (But I can’t get to it until next week, need to change passwords etc first). Send me your email address if you’d like to give it a try Edited January 28, 2022 by MarkTilles Quote Link to comment Share on other sites More sharing options...
newps Posted January 28, 2022 Report Share Posted January 28, 2022 Hi Mark, I would be interested to give that a go as well. Don't know how MS OneDrive works (i'm on a mac) Newps Quote Link to comment Share on other sites More sharing options...
MarkTilles Posted January 28, 2022 Report Share Posted January 28, 2022 (edited) 7 hours ago, newps said: Hi Mark, I would be interested to give that a go as well. Don't know how MS OneDrive works (i'm on a mac) Newps No problem I use Mac for my hobbies as well. Just use the raspberry pi imager tool and select my file as the source image to write onto your sd card. I can send a link you can download the image from my OneDrive. But I need to genericize it first. Please note my image has features not in Jbruce’s fork (not to mention a link to swapping between two instances of the kiln controller located in two separate folders). I use the same hardware to control two different kilns with toggle switches to swap between thermocouples- and this is working for me … Email me at markt3ATATATATtilles.net Edited January 29, 2022 by MarkTilles Quote Link to comment Share on other sites More sharing options...
Mark Henshaw Posted January 28, 2022 Report Share Posted January 28, 2022 1 hour ago, rondoc said: instruction on github site and it works until I get this "ERROR oven : problem readi Looking through my version of the code (downloaded Dec 2019, modified here and there since), the error likely stems from one of the following errors reported by the maxim chip: "No Connection" "Thermocouple short to ground" or "Thermocouple short to VCC." I've had problems with my setup where the TC leads connecting to the AdaFruit posts crossed (though this results in an erroneous reading, not a software exception). Perhaps re-check your connections and check that the TC is not grounding to the kiln frame? regarding the IP address not working for you, this depends on your home network's local address and the specific address assigned to your PI. there are a couple of things to try if thats still not working for you. If you like, I can also dig up some python code I used to directly read and report the TC values on the PI screen to help localize the troubleshooting Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 28, 2022 Report Share Posted January 28, 2022 2 hours ago, MarkTilles said: Rondoc, i have a working ISO image of 7.5 GB card I can share with you on MS OneDrive. It’s set up with a Pi zero w and max31856 if you might want to give it a whirl? (But I can’t get to it until next week, need to change passwords etc first). Send me your email address if you’d like to give it a try That's very kind of you. I am going to try a max 55 board and see if that works. The fail is something to with the way oven checks the TC output. It might also need a pi4B not the 3B I have now. My email is rdoctorsAaagmail.com and it would be easier for me for us to communicate via emails. The pi 4 are expensive right now so I'll wait..May be just the zero is all I need. It will be dedicated to the kiln . Thanks.Ronald Quote Link to comment Share on other sites More sharing options...
rondoc Posted January 28, 2022 Report Share Posted January 28, 2022 58 minutes ago, Mark Henshaw said: Looking through my version of the code (downloaded Dec 2019, modified here and there since), the error likely stems from one of the following errors reported by the maxim chip: "No Connection" "Thermocouple short to ground" or "Thermocouple short to VCC." I've had problems with my setup where the TC leads connecting to the AdaFruit posts crossed (though this results in an erroneous reading, not a software exception). Perhaps re-check your connections and check that the TC is not grounding to the kiln frame? regarding the IP address not working for you, this depends on your home network's local address and the specific address assigned to your PI. there are a couple of things to try if thats still not working for you. If you like, I can also dig up some python code I used to directly read and report the TC values on the PI screen to help localize the troubleshooting The TC is in the open air so no accidental connection . It says Fail GND , VCC and ??? . I don't think much of the GPIO pins on my pi, they are smaller than I'd like. However the readout is always fine until the ERROR so I think it's software not hardware. I think you're right the Adafruit is reporting the ERROR so may be it is the problem. Changing to a simple max 55 board will at least change the scene...I'll keep you posted. (The 55 doesn't come until Monday 31st.) Much Thanks Ronald. Quote Link to comment Share on other sites More sharing options...
cadenrank Posted January 29, 2022 Report Share Posted January 29, 2022 5 hours ago, rondoc said: and checked by a Fluke all the time. This is repeatable. Help please. How exactly do you have it wired that you're able to check it with the Fluke? Do you just unplug it and plug it into the fluke? Or is the fluke wired in too? Quote Link to comment Share on other sites More sharing options...
cadenrank Posted January 30, 2022 Report Share Posted January 30, 2022 (edited) Things worked well once I got it figured out on the pi, and am successfully monitoring temperature from the thermocouple now, and it performed as expected during my last firing. I don't know that I have the confidence in it just yet to actually set it up to control (this really wasn't my intention anyways, but still cool to have the option), but I'm very satisfied with the ability to see the thermocouple values remotely, and to be able to graph them out if I wanted. Anyone have any other ideas/schedules or anything like that that would make this work even better just in regards to monitoring temperature? Edited February 1, 2022 by cadenrank Quote Link to comment Share on other sites More sharing options...
cadenrank Posted February 2, 2022 Report Share Posted February 2, 2022 I direct this at @Bill Kielb because I think I've seen him comment about it before, but anyone else is welcome to answer too if they know: Would it be not a good idea if instead of connecting the thermocouple wires directly to the 31856 board (photo for reference), could I instead connect a female type K connector to the max 31856, and a male type K connector to the thermocouple wires and make a junction that way? Or would it make any kind of difference? again, this is just being used to monitor temperature remotely, there's no control happening. The only reason I want to do this is just in case of any issues, I can still use my pyrometer as I normally would just by unplugging it at the connector and then plugging the male end into the pyrometer. I already bought the connectors from Amazon, but wanted to make sure that this wouldn't cause any issues in regards to temperature reading before I did it. connector imaged below: Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 2, 2022 Report Share Posted February 2, 2022 1 hour ago, cadenrank said: I instead connect a female type K connector to the max 31856, and a male type K connector to the thermocouple wires and make a junction that way? It should work fine. Thermocouple connections don't affect the reading as long as there's no temperature difference across the connection, which there never is with small connector. That's why you can use standard terminal blocks for thermocouple connections, like most kiln companies do. cadenrank 1 Quote Link to comment Share on other sites More sharing options...
rondoc Posted February 2, 2022 Report Share Posted February 2, 2022 23 minutes ago, neilestrick said: It should work fine. Thermocouple connections don't affect the reading as long as there's no temperature difference across the connection, which there never is with small connector. That's why you can use standard terminal blocks for thermocouple connections, like most kiln companies do. You can just connect them together . Paralleling the wires is fine. I use my Fluke in parallel with the max board so I can check them . cadenrank 1 Quote Link to comment Share on other sites More sharing options...
MarkTilles Posted February 2, 2022 Report Share Posted February 2, 2022 (edited) 26 minutes ago, neilestrick said: That's why you can use standard terminal blocks for thermocouple connections, like most kiln companies do. Ah!! That’s why my use of DPDT toggle switches to switch between two different kiln thermocouple cables and a terminal block is still providing reliable results! Thanks for this! Edited February 2, 2022 by MarkTilles cadenrank 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 2, 2022 Report Share Posted February 2, 2022 24 minutes ago, MarkTilles said: Ah!! That’s why my use of DPDT toggle switches to switch between two different kiln thermocouple cables and a terminal block is still providing reliable results! Thanks for this! Yep. Basic common toggle switches were standard on Alpine kilns to switch between top and bottom thermocouples for decades. Lots of old kilns had them before the days of controllers and pyrometers that have multiple thermocouple inputs. cadenrank 1 Quote Link to comment Share on other sites More sharing options...
cadenrank Posted February 2, 2022 Report Share Posted February 2, 2022 (edited) Alright so, follow up: I did this, and the pyrometer is reading 64 degrees F, and the pi is reading 34 (which is what it read prior to adding the connectors, and is more likely closer to the actual temperature. I never used the pyrometer originally when I installed it because I knew what the temperature of my garage was, and the pi was matching it, so I'm not for certain if it always had this difference or not. This pyrometer also has given me funky readings in the past, so I'll try again later and see what it reads. I figured if there would be any issues or differences it would be on the pi's end, since it had to go from male connector, to female, and then to the max 31856, where the pyrometer is just going from the thermocouple, to the male connector, to the pyrometer. Edited February 2, 2022 by cadenrank Quote Link to comment Share on other sites More sharing options...
cadenrank Posted February 2, 2022 Report Share Posted February 2, 2022 29 minutes ago, cadenrank said: Alright so, follow up: Disregard this. After a checking again, they were both matching each other this time, and then when I gave the kiln some power to heat it up, they both got up to about the same point as well. I did learn that the connectors I bought fit backwards or normally into my pyrometer, so I'll have to keep an eye on the negatives and positives when I plug into my pyrometer. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 2, 2022 Report Share Posted February 2, 2022 2 hours ago, cadenrank said: This pyrometer also has given me funky readings in the past, so I'll try again later and see what it reads. I figured if there would be any issues or differences it would be on the pi's end, since it had to go from male connector, to female, and then to the max 31856, where the pyrometer is just going from the thermocouple, to the male connector, to the pyrometer. Thermocouples can appear backwards in polarity because they are often viewed as a power source. Anyway simple to check calibration over a small range with ice water and boiling water. For higher approximates a propane torch can see if it accelerates in the thousand degree range. If your meter presents too much load the reading can be affected by parallel operation. .thermocouple wire and thermocouple connectors are supposed to be made of compatible metals as the thermocouple so as not to induce additional couples. Most folks use thermocouple wire and jacks made just for thermocouples which are made of compatible materials, others don’t contending equal and opposite couples are created and negate each other. Still some are susceptible to noise and require shielded thermocouple wire. For the most part they are robust and tolerate reasonable connections cadenrank 1 Quote Link to comment Share on other sites More sharing options...
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