I decided to start a new post so I wasn't taking over SmokinStu's thread. Anyway this is my previous post.
"Here's my current PID numbers:
P=400
I=225
D=225
I have ran the AT 3 times now. Each time the settings are a little different but the outcome is almost the same. I am currently doing 2 butts at 210 degrees with a temp swing of 2 degrees each way. Does anybody have any thoughts on which setting I should try tweaking and in what direction? I would be interested in hearing what anybody else's settings are."
Interestingly enough, it is now just about 8 am so the butts have been in about 12 hours. They are now at 160 degrees. The interesting part is every time I've checked it this morning the temp has been dead on 210 degrees. Does the Auber PID "learn", so to speak, as time goes on? Or, is it more a factor of the contents of the tower just coming to a more stable temp?
I would still like to here what other peoples P,I & D numbers are and what other mods they have done that might influence it such as circulation fans.
Mike
PS:
Each time I ran the AutoTune I set the target temp at 200 degrees. My last 2 smokes were jerky at 165 degrees. Thinking about this, the reason I had a slightly larger temp fluctuation may have been because of this?
Again right now my target temp is 210 degrees which is very close to the AutoTune temp of 200 degrees.
Mike
Just plugged in my PID and tried it out. No sparks, no fires. Now it is a couple of degrees below freezing outside and the winds blowin with a storm coming in, so my empty smoker had a hard time getting up to 200 degrees. I wish the BS came with a more powerful heater.... may be my next upgrade.
P=10, I=257. D=3 for my autotune. Not really sure what that means.
I will wait for a warmer day and prep some food for the BS and really try out the PID.
Stu
I saw the picture of yours in the other thread.... Looks excellent!
I would probably run your auto tune again when you have more favourable weather. The wind and outside temp will definitely have an effect on the auto tune. I read on here somewhere, I think it was BubbaGrump, he would set the temp to 200. Then when it was at about 190 he would put 2 bricks on a rack in and turn the auto tune on. He said the 2 bricks would simulate a load in the BS.
Too bad about the weather, but keep me informed how you make out.
Mike
Hello
Been using a Guru/Raptor setup for 2 yrs now and am starting to have problems with it ,so I read until my eyes bled and built a PID from all the info I found here (you will notice this is my first post as I have been reading this forum for almost 3 yrs and never had a question till now) PID build went find, testing went fine , used autotune as best as I could make out how to do it, here are my readings after the 2nd auto tune (I knocked the plug out on the 1st one) everything is still on now Temp read on PID 201
Temp set on PID 200
P 624
I 472
D 384
Maverick reads 197
How can I tell which temp reading is correct? Maverick or PID?, I Am using Auber PID and Omega TC
Thank You
Hi Carnie1
Welcome to the forum.
I think I read a couple of different threads. One used boiling water to put the TC in as water boils at 212 degrees. The other one used ice water which should be 32 degrees. I haven't tried either one but I was planning on it. You may find the difference between them may have more to do with the placement of the TCs in the box. If you find it is the PID I believe there is a setting for it.
Mike
Thanks for the quick reply, there a probably a lot of variables here, I'm just trying to figure the right one, will do the boiling water , ice water thing for the Maverick tomorrow. Thanks again
@ NePaSmoker "Maroon and vite........ Maroon and vite.... those are the colors for vitch ve vite " I'm sure you'll understand this, we are probably neighbors I work out of that area, I'm not there now but will be back north in the spring.
Been about an hour and a half since my first post(someday I'll learn how to set forum times) and Mav reads 196 temp set is 200 and TC read is 202 , gonna shut it off now and give it another run tomorrow.
Quote from: carnie1 on February 26, 2007, 05:56:06 PM
@ NePaSmoker "Maroon and vite........ Maroon and vite.... those are the colors for vitch ve vite " I'm sure you'll understand this, we are probably neighbors I work out of that area, I'm not there now but will be back north in the spring.
Carni1 I have not a clue ??? to what you mean. I am a newbie to the area (3 years) In PA for 9 years Lancaster County and am a S. Calif native. But anyways hi neighbor ;D
nepas
Quote from: carnie1 on February 26, 2007, 06:17:12 PM
Been about an hour and a half since my first post(someday I'll learn how to set forum times) and Mav reads 196 temp set is 200 and TC read is 202 , gonna shut it off now and give it another run tomorrow.
Welcome to the forum. I've been using the Guru for about 2.5 year the only problem I've had was the TC. I pulled the wire out of the probe; my fault. Replaced the probe and every thing is fine.
As to the boiling point of water, other factors do play a role. Altitude and the current barometric pressure have and effect on the boiling point. Here is a site that will assist you in determining the boiling point for your location and weather conditions.
http://www.biggreenegg.com/boilingPoint.htm
If you don't know your barometric pressure use the default value they provide.
This is the method I use to check probes, tend to use boiling point rather than melting point as it better reflects the sort of temperatures we are using in the BS:
Boiling Point Method:
Bring clean tap water to the boil in a deep pan.
Put the thermometer stem or probe into the boiling water so the sensing area is completely submerged. Take good care not to scald yourself.
Do not let the probe touch the pan bottom or sides.
Wait 30 seconds or until the indicator stops moving.
The thermometer should read 212F, (100C) or the appropriate boiling point for your elevation. (see above)
If it does not fall within an acceptable range (+/- 5F/2C) the thermometer should be recalibrated according to the manufacturer's instructions, if indeed it can be recalibrated. Not all thermometers can be.
If the thermometer is under warranty it should be returned to the manufacturer.
If the thermometer is inaccurate, is not under warranty and/or cannot be adjusted it should be discarded. Any false reading at the boiling point of water may not be linear; i.e. it could be more (or less) inaccurate at different temperatures.
The boiling point of water is about 1F (0.5C) lower for every 550 feet (168m) above sea level but see the post from HS above regarding your location.
I check mine every 6 months.
ManxMan & Habanero Smoker
Great information and links guys!
Mike
BigSmoker provided that link some time ago. It is very helpful. As a general rule, for my elevation, the boiling point is 110.9°F.
Quote from: Habanero Smoker on February 27, 2007, 02:06:26 PM
BigSmoker provided that link some time ago. It is very helpful. As a general rule, for my elevation, the boiling point is 110.9°F.
What the heck are you doing 10+ miles above sea level? ;) :D
TYPO; I think Hab meant 210.987654321 F ;D ;)
Either that or he's playing around in space again and not telling us. :o ;D
I think it's the latter. ;D
Thanks for all the help, I didn't get a chance to test Maverick yet, I talked to BBQ Guru and they are gonna check my setup out
NePa I was makin fun of the "Dutchie" talk about the school colors
oh ok i gotcha now.
becareful amongst the english.
nepas
Just for the heck of it I ran my altitude and the current barometric pressure on the link and it show 208.9 degrees. I didn't realize it would make that much difference. :o
Mike
Ran mine and came up with 209.3. Now I just gotta build a PID so I can put this knowledge to use. Anybody know where I can get a thermocouple cheaper than $30?
Quote from: Tiny Tim on February 27, 2007, 02:23:07 PM
Quote from: Habanero Smoker on February 27, 2007, 02:06:26 PM
BigSmoker provided that link some time ago. It is very helpful. As a general rule, for my elevation, the boiling point is 110.9°F.
What the heck are you doing 10+ miles above sea level? ;) :D
Sometimes I need to get clear of all the smoke, and the other stuff floating around down there ;)
Iceman is correct it should have been 210.9°F, depending on the barometric pressure.
OK I finally decided to put some food in and try out the PID, I'm doing bacon wrapped chicken and a small turkey breast. During testing the heat went right up and stayed within a few degrees now I have the PID set at 220 but it wont go above 199 and it went right to 220 on the pre heat, it's about 80 outside with a little breeze, Any Ideas? Thank You
Hmmm, It's right on the money now at 220 and it cooled down to 74 outside but of course I'm done now.
Not sure how much food you had in the smoker but the food will absorb heat and keep the temps down until it starts to warm up. Moisture (Chicken / Bacon) also absorbs heat so if the vent was pretty nearly shut that may have had an effect as well. Thinking it may not be your PID - Other PID user will know better.
Carnie1
Did you get it working correctly?
I've been away for a couple of days and just saw your post. When you ran the auto tune did you have any kind of load in the tower?
Mike
P= Proportiomal, I- Intergral, and D= Derivative, these are all functions of the PID> Math stuff, anyway the most important one to tweak would be the derivative, most controllers have zero set for derivative. this is a function of how fast the controller reacts to change in temp. so when you open the door the pid ramps way up and swings around set point. or if there is a slight over shoot, the pid ramps way down. Try to dial the d all the way down and see what happens, however remember the setting you are currently at just in case
Thanks Sabre.
What I think would help everybody, especially me, is to have more of a "laymans" description of what spacifically the Auber P, I & D settings do in this exact installation, ie the Bradley Smoker. Here is what the Auber manual says regarding the settings:
6.6.1 PID
Please not that because this controller uses fuzzy logic enhanced PID control software, the definition of the control constants (P, I & D) are different than that od traditional proportional, integral, and derivative parameters. For the first time user, we strongly suggest you use the Auto Tuning function to set the PID parameters first (see 6.3). If the auto tuning result is not satisfactory, you can manually fine-tune the PID constant for improved performance.
(1) Proportional constant "P"
Proportional action is the action that the control output varies in proportion to the deviation between the set value and the measured temperature. Larger proportional constant means quick and larger action. However, if the proportional constant in increased too much, even slight distubances may cause variation in the processing temperature. Control action starts to behave like ON/OFF action and the hunting phenomenon occurs. Please note the P is not defined as Proportional Band as in the traditional model. Its unit is not in degrees. The Larger the constant results in larger and quicker action, which is the opposite of the traditional proportional band value. It also funtions in the entire control range rather then a limited band.
(2) Integral time "I"
Integral action is used to eliminate offset. Larger number means slower action. When temperature fluctuations regularly (system oscillations), increase the integral time. Decrease it if the controler is taking too long to eliminate the temperature offset. When I=0, the system becomes a PD controller.
(3) Derivative time "D"
Derivative action can be used to minimize the temperature over-shoot by responding to its rate of change. The larger the number the faster the action.
So, based on this wealth of information ::) does this mean...
The higher you set P the faster and more power it applies to the heating element based on the temp difference. Does this setting affect anything when the tower temp is higher than the target temp?
The "I" setting, hmmmmm. Lets see, first off is "offset" described as a temp swing both above and below the target temp? If it does apply to both I'm really confused. Larger number means slower action. What action?
The "D" setting controls over-shoot. The larger the number the faster the action. I am assuming over-shoot is when the tower temp is higher than the terget temp.
Everytime I read through this and think I have it, I just get further confused. Man this is so far over my head and I'm even standing on a chair! ;D
:D
Mr Walleye,
Your startig to sound like an instrument technician!!! Yes over shoot is the amount above and bellow setpoint yuor process varries, Derivative is not allways your friend. Good luck with the tuning, Im sticking to the slider on the OBS, if I have to spend more time fooling around with the temp, thats less time for the honey-doo list... plus it only takes one hand, the other is free for my favorite refreshment!
Quote from: Sabre on March 03, 2007, 11:25:25 AM
Your startig to sound like an instrument technician!!!
::) ::) ;D
Actually I have mine working good. I was just trying to understand it better and mybe help anybody else trying to fine tune their's.
Mike
Mr. Walleye,
Not bad. The P term "amplifies" the error term (setpoint - current temp). The higher the P value, more correction (in this case power up or down) is applied for a given error.
For a number of reasons, Proportional control will not drive you to zero error. So the Integral term is used to sum up these small residuals errors and help drive it to zero. However, since it sums previous errors (which can be quite large if you are far away from setpoint), it must be used with care and is usually bounded.
The derivative term is used to "anticipate" what to do upon a change in setpoint. Higher values cause more or less power to be applied quickly.
He is a link with some more information: http://www.htservices.com/Applications/Process/PID2.htm
Arcs_n_Sparks
It;s supposed to go above freezing here next week, and I will try out my PID then. This waiting around for nice weather to try out my new toy is driving me nuts.
Reminds me of when I got a new bike for Christmas one year and had to wait months for the snow to melt so I could try it. :'(
The new bike for me was 4th grade. Did not get to ride it until my birthday in march ... was a killer.
When you tune the pids do you have to have a puck burning also. Just wondering if the profile is effected by that type of thing. Not sure if a smoldering puck changes things any?
The first 2 times I ran auto tune I did it with the SG on but no pucks and the tower was empty. Both times the numbers ended up almost the same. Then on the following weekend I was doing a couple of butts and decided to put the PID into auto tune mode. The result was my current set of numbers which are different from my other 2 attempts. The PID seems to be pretty much spot on now. Once in a while it will flash + or - 1 degree. I remember reading BubbaGrumps post about using a couple of bricks in the tower to simulate a load. I think when running the auto tune this is fairly important.
Mike
Well, I ran the autotune on the new PID today. The first time was with the smoker shack door open and I got a PID or 472, 215, 279 respectively.
I then re-ran the autotune with the smoker shack door closed as I would normally smoke and I got 0, 185, 0........ Not being sure what the heck that meant I redid the autotune a third time with the shack closed up and got 362, 9250, 147.
I am not sure what the heck is happening here. The temp looks good and I guess that is what counts. I had water in the BS but no food. I think I will go with it and when I do a butt, I will wait past the first two or three hours and then run the autotune then, with the butt in and everything warmed up.
The BS door thermometer reads 195 degrees, the ET-73 says 220 degrees, and the PID says 215 degrees, which is where I set it. I think I will bring a thermister home from work that I know is accurate and then calibrate the actual temp on my PID with that.
Tell me, if I bought a new digital BS, this is all built in, no?
Here is a link to my experiences with the temp swing on the DBS. Tipically I would see a swing of 189 to 207 with a target temp of 200. I guess out of the box you do have the ability to control the temp enough feel reasonably ok to leave it un attended. Although lots of people here feel the same way about the OBS.
http://forum.bradleysmoker.com/index.php?topic=4740.0
Mike
I just put together a new pid and autotuned it. Once its autotuned, do you have to autotune it every time you change the set value?
Rick
Hi LoneStar
No you don't have to. The only time you would rerun the auto tune is if you change something that influences the ability of the unit to heat the tower. Like adding a circulation fan or something like that. As I have indicated earlier I have ran auto tune several times and recorded the numbers, the most recent was while doing a butt. This setting seems to be the best for me so I would recomend running the auto tune with a load in. JMHO
Good Luck
Mike