Troubleshooting Help


 

Dan Seaver

New member
I just did my first low and slow cook and I had two issues that I need help troubleshooting.
12 hours into the cook one of the meat probes dropped to off (probe2). I had probe1 and probe2 in service. So to see if it was an issue with the probe...I pulled probe2 and moved it to probe3 and I got a reading...moved it back to probe2 still nothing. I pulled the power plug rebooting the whole thing and probe2 began working again. The problem is I lost the graph of the cook. So one question I have is what should I have done to troubleshoot this problem to not lose the data. What would make the probe drop to off during a long low and slow cook. This problem repeated again 6 hours later.

Also the probes were brand new.

Thanks,
Dan
 
That's definitely odd that if you plugged it into a different jack it worked fine and if you rebooted it worked fine. Are they ET-732 probes by some chance? They seem to exhibit mystery symptoms if the braid isn't grounded.

You could try rebooting just the HeaterMeter when it happens, which won't affect the graph. LinkMeter -> Configuration -> Reboot AVR (bottom of page)

To keep the graph across reboots, you need to stash it and restore it.
Before rebooting: LinkMeter -> Archive -> Stash
After rebooting: LinkMeter -> Archive -> Activate as current

Version 9 has an auto-backup feature that makes this part all automatic, only losing a max of 5 minutes of graph data if you suddenly reboot.
 
I purchased the Maverick prob for my pit but made a stupid assumption that my old iGrill food probes were the same probe.... Does anyone happen to know the coefficient settings, resistance for the iGril probes? It would be a great help if anyone does... Otherwise I will have to take a day tomorrow and attempt to measure and document them, if I get it before anyone else I will definitely post! Thanks

Nick
 
Bryan,

Thanks for the reply. I had an et-732 probe in the pit jack...all meat probes were et-72 high temperature probes (brand new). I did not have any issues with the ET-732 pit probe, from other postings I am aware of the mystery symptoms...I think I started a thread regarding the drop out of the temp reading causing the blower to turn on and off.

Is having to reboot the heatermeter a common occurrence? It seems strange that it worked fine for 12 hours and then dropped out.

Dan
 
It should not be. I run my HeaterMeters 24/7 so I can do development on them, with probes attached as well as RF nodes. I never have to reboot them, the AVR nor the rPi. There's no blower/servo connected to them so maybe that has something to do with it? I'll plug a blower in and see if that messes with things.
 
I have measured the resistance on my iGrill Probes at a few different temps and was able to determine the coefficients. I think that they could be better had my ohm meter been of higher quality. I find the temp to be very close to the same reading as my Maverick ET-73.

iGrill Grill Probe
A=0.00078840856
B=0.00019713984
C=1.9405889e-7

I would like to get a better measurement to get this more dialed in, is it possible to read resistance or plot to a chart with the heater meter? Can I read instance resistance via ssh to the rpi?

Nick
 
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I have measured the resistance on my iGrill Probes at a few different temps and was able to determine the coefficients. I think that they could be better had my ohm meter been of higher quality. I find the temp to be very close to the same reading as my Maverick ET-73.

iGrill Grill Probe
A=0.00078840856
B=0.00019713984
C=1.9405889e-7

I would like to get a better measurement to get this more dialed in, is it possible to read resistance or plot to a chart with the heater meter? Can I read instance resistance via ssh to the rpi?

Nick

This is great info as I was wondering if I'd be able to use my iGrill probes with the HM that I'm building. Do you happen to have the ambient/grill probe as well? If so, would it be the same coefficient?

I've got a couple of digital multimeters I can test with. How would I go about testing my own iGrill probes?
 
That was for the ambient igrill grill probe. They do appear to be the same for the meat probes as well.

So to do your own measurements you will need to be able to provide some very consistent temps to allow yourself enough time to capture the temp and resistance reading.

You will need to document the following temps
Resistance at 40f
Resistance at 77f
Resistance at 200f

You can very these temps but you will want to make sure you get a decent spread. Do not immerse the probe in water as water entering the lead end of the probe an damage the probe.

Once you have at least the three value pairs of temperature and resistance go to the link below and use the java applet calculator, enter in your values. It will return your coefficients. Copy and paste each of them into your configuration for the probe on the web page. Test your values with your temp gauge used for testing. I used my oven to watch it heat up and cool down. I found that the temp curve follows the ET-73 pretty well. The temps are not exactly the same but I don't have different slopes anymore.
http://www.capgo.com/Resources/Temperature/Thermistor/ThermistorCalc.html

Post the values you come up with so I can compare to mine and test the new values.

Bryan, what are the chances of editing files directly from the PI to add our own presets for different probes? Or would this be something that you just add to the array on the source file?

Nick
 
Thanks for the info.

I'm using the iGrill to measure the following temps.

Popped the probes into the fridge and they went down to 42F

At 42F/5.55C , one read 248K ohms and the other read 247K ohms
At 88F/31.11C , one read 76K ohms and the other read 75K ohms
At 220F/104.44C , one read 5.67K ohms and the other read 5.62K ohms

Also, for whatever reason I didn't think of using the pit probe until the last reading. When the meat probes were reading 220, the pit probe was at 226 and had a reading of 5.22K ohms.
 
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Thanks for the info.

I'm using the iGrill to measure the following temps.

Popped the probes into the fridge and they went down to 42F

At 42F/5.55C , one read 248K ohms and the other read 247K ohms
At 88F/31.11C , one read 76K ohms and the other read 75K ohms
At 220F/104.44C , one read 5.67K ohms and the other read 5.62K ohms

Also, for whatever reason I didn't think of using the pit probe until the last reading. When the meat probes were reading 220, the pit probe was at 226 and had a reading of 5.22K ohms.

Steve,

I came up with the same numbers. I did notice that the pit probe was a bit different and I had included different coefficients for that probe. I also took my lower two numbers and used your higher number and came up with the same values for the pit probe. So these should be pretty close. I find that the temps are slightly off but the curve is very very close to the ET-73. So you should be able to just use the offset to line them up a bit better.

iGrill Pit Probe:
A=0.00078840851
B=0.00019713984
C=1.9405889e-7

From Your Readings:

iGrill Meat Probe 1:
A=0.00078840856
B=0.00019713984
C=1.9405891e-7
 
I would like to get a better measurement to get this more dialed in, is it possible to read resistance or plot to a chart with the heater meter? Can I read instance resistance via ssh to the rpi?
You'll need a lot more points over a larger range to get accurate coefficients I think.

You can set HeaterMeter into resistance mode, which outputs the pit temperature in Celsius, and the other probes in Ohms. You'd put a known probe in the pit slot then the one you're trying to figure out in FOOD1. To do that just set the setpoint from the configuration screen to '0R' (zero R), or really anything ending in R. You can then use `lmclient LMSU` to get the values or `lmclient @LMSS` to get streaming updates.

Even better but not really tested is the Unknown Probe mode:
Code:
# set linkmeter to unknown probe mode which sets heatermeter resistance mode
lmclient LMUP,1
# now put both the known and unknown through some temperature range
...
# Finally output the resistance table to a file
lmclient LMUP,0 > unknown.csv
unknown.csv should be a table of temperature -> resistance you can then use in the calculator app. I will caution you to try it first over a short range of temperatures to see if it works, because I've never done a full test of this before.

EDIT: And you can edit the source to add more presets to the list, but I'd have to do it in my source otherwise your changes will be wiped out every time you upgrade.
 
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I sent an email to the folks at iGrill earlier today asking if they'd be able to get someone to provide me with the info on their probe thermistor resistance and calculated coefficients based on the standard Steinhart-Hart equation.

I'll be sure to post any info I receive.
 
Bryan,

I was successful. I was able to read from 0c to 100c about 297 lines of data. I did this for 3 iGrill probes and some other one that I am not sure who makes the thing. I will let you know what I come up with for the coefficients. I will also try to detail out how I did this successfully and PM to you for review. You can do with it what you please, post it or toss it. :)

Nick

You'll need a lot more points over a larger range to get accurate coefficients I think.

You can set HeaterMeter into resistance mode, which outputs the pit temperature in Celsius, and the other probes in Ohms. You'd put a known probe in the pit slot then the one you're trying to figure out in FOOD1. To do that just set the setpoint from the configuration screen to '0R' (zero R), or really anything ending in R. You can then use `lmclient LMSU` to get the values or `lmclient @LMSS` to get streaming updates.

Even better but not really tested is the Unknown Probe mode:
Code:
# set linkmeter to unknown probe mode which sets heatermeter resistance mode
lmclient LMUP,1
# now put both the known and unknown through some temperature range
...
# Finally output the resistance table to a file
lmclient LMUP,0 > unknown.csv
unknown.csv should be a table of temperature -> resistance you can then use in the calculator app. I will caution you to try it first over a short range of temperatures to see if it works, because I've never done a full test of this before.

EDIT: And you can edit the source to add more presets to the list, but I'd have to do it in my source otherwise your changes will be wiped out every time you upgrade.
 
OK that is too cool!

dave

You'll need a lot more points over a larger range to get accurate coefficients I think.

You can set HeaterMeter into resistance mode, which outputs the pit temperature in Celsius, and the other probes in Ohms. You'd put a known probe in the pit slot then the one you're trying to figure out in FOOD1. To do that just set the setpoint from the configuration screen to '0R' (zero R), or really anything ending in R. You can then use `lmclient LMSU` to get the values or `lmclient @LMSS` to get streaming updates.

Even better but not really tested is the Unknown Probe mode:
Code:
# set linkmeter to unknown probe mode which sets heatermeter resistance mode
lmclient LMUP,1
# now put both the known and unknown through some temperature range
...
# Finally output the resistance table to a file
lmclient LMUP,0 > unknown.csv
unknown.csv should be a table of temperature -> resistance you can then use in the calculator app. I will caution you to try it first over a short range of temperatures to see if it works, because I've never done a full test of this before.

EDIT: And you can edit the source to add more presets to the list, but I'd have to do it in my source otherwise your changes will be wiped out every time you upgrade.
 
I was successful. I was able to read from 0c to 100c about 297 lines of data
Sweet! I'll have to admit I was a bit nervous about you going through this procedure then having there be a bug that would have caused the whole thing to crash and lose your work. I've done the procedure manually before and fed it into the AN2395 application which is what we use for our preset coefficients now.

Dave: Yeah I was working on a web interface for doing unknown probe calculation, that would even integrate the curve fitting algorithm to just spit out A,B,C. But turns out we haven't had much use for doing the calculations and the code behind AN2395 boggles my mind so I've just ignored porting it to lua. :-D
 
Bryan,

I think I need to get more of a range. I only took a range from ice water to boiling water. I am going to run a more full scale test on one of my probes tonight. I did find a project that had some java code that I pumped my CSV values into. It may be possible to just compile the c version and load on the rPi as a utility, then pass the .csv via a shell script called by the lua code when you execute lmclient LMUP,0 > p1.csv. Then after that runs have the script get the coefficients and push to the Presets, or just directly set the probe coefficients.

Here is a link to the library I found. http://thermistor.sourceforge.net/

The java code I wrote uses the library and outputs the Coefficients and resistance table. I am sure it could also be a friendly utility built into the PitDroid android app.

I will do some more testing tonight and let you know how it goes. I hope to have the probe temps match up nicely to my Maverick, just need a larger range over the 210F mark.

Nick


Sweet! I'll have to admit I was a bit nervous about you going through this procedure then having there be a bug that would have caused the whole thing to crash and lose your work. I've done the procedure manually before and fed it into the AN2395 application which is what we use for our preset coefficients now.

Dave: Yeah I was working on a web interface for doing unknown probe calculation, that would even integrate the curve fitting algorithm to just spit out A,B,C. But turns out we haven't had much use for doing the calculations and the code behind AN2395 boggles my mind so I've just ignored porting it to lua. :-D
 
So this didn't go as well as I had hoped. I believe the issue stands with the probe used for calibrating. I am using the Maverick ET-73 Grill Probe. As mentioned in some other posts it is not a very fast acting temperature probe. Digging in my memory banks I remembered that there are a few different ways that the thermistor can be mounted in the sheath. When I test the resistance from the ring of the jack to the sheath of the thermistor it is 0 ohms. When I test the resistance from the tip of the jack to the sheath there is no connection. When I tested the iGrill ambient the same way the sheath and the tip had a resistance. This leads me to believe that the Maverick is an ungrounded thermistor and the iGrill is a grounded thermistor. The grounded thermistor has a much faster response time than the ungrounded.

So the Maverick is very slow to respond and the iGrill is very fast to respond that means that the iGrill will already be reading the higher temp while the Maverick is still trying to catch up. After running the numbers though the coefficients are WAY off. I used this weekend and found that the best numbers I have today are the original ones that I came up with measuring the ohms with my meter and document. I found that with the coefficients listed higher in the thread I was very very close to an accurate temp. I use the iGrill to measure the "Dome" temp at the very edge of the grill and the Maverick measures the temp in the center 2" from the meat. The iGrill on the edge of the grate nearest to the dome most always was dead on with the dome temp on the Big Green egg. There were times when it evened out and the center and edge were close to the same as the meat temp would rise.

I will try to contact a temperature sensor OEM sometime soon and find if there is a faster acting probe I can get to better calibrate these iGrill probes, as well as find a source for some faster acting temp sensors with known coefficients.

Nick
 
I'll try and run some wide-range temp logging on my iGrill probes. I'll use the iGrill with 1 probe as a known source and I'll have my other 2 iGrill probes hooked up to a SysComp CircuitGear allowing me to do a resistive log against the other 2 probes.

I'll take pictures or video of the iGrill and macbook screen and then manually plot the numbers.
 
I finally heard back from iGrill support. I somewhat expected this response, but it's still somewhat disappointing.

Hi Steve,

Thank you for taking the time to contact our customer support team. Due to current MFi restrictions from our development partners, we are unable to share specifications for our products or software at this time. We sincerely apologize for the inconvenience and appreciate your understanding.

Thanks,

Customer Support Team

iDevices, LLC
 

 

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