Wiring PID and SSR = need some help

[flyweed]

Dick...I am in Wisconsin.where I live we are 700 feet above sea level.  So would that make a difference?

Also...I set the autotune as I stated earlier...it is now  8.5 hours later and the autotune light is still blinking...I thought this was suppose to go solid after it "tuned" itself.  Did I do something wrong?

Dan

 

[hughjass]

Dan

Can't answer the second part of your post, but here's a link for the first.  Just plug in the elevation and the barometric pressure, and you'll have your boiling point.  (you can get current barometric readings from the weather channel or other weather url.  It looks like your boiling point is 210.5~, but please double check it.

http://www.csgnetwork.com/h2oboilcalc.html

Had an epic failure today on my build.  Either I've the wrong voltage from PID to SSR or the SSR was defective.  Going to check the voltage output on the PID tomorrow.  Either way, the SSR stayed open and melted itself and the control box.

  It's a good thing I was keeping a good eye on it.  Anyway, congrats on your success.  Prost!

 

[flyweed]

ah damn....well just figured out why my AutoTune is still blinking away.  I never plugged the damn fan in!..so  the PID was reading Temps...but the fan could not turn on and off to raise the temps..so I assume this is why the Autotune never "tuned" itself...would this be why??  or wouldn't that matter

Dan

 

[flyweed]

hope you guys aren't sick of me posting yet.  I went out today and did the boiling water test again.  I made sure the probe was well submerged, and water was at a full rolling boil...same temp = 207F....so I hit the set butto, type in 0089 and scrolled down to the psb setting...I typed in the number 0005..again, my instructions say NOTHING about adjusting the temp..so I just assumed the number corresponded with degrees....and so I hit "set" and started the boiling water test again....got to a full rolling boil..fullly submerged the probe..let it come to temp...and sit in the rolling water for 5 minutes...hit 212F and did not move one degree the entire time.

So I think I have the temps on the PID set dead on now.  now it's time to smoke something else, and make sure the blower is plugged in, and hit autotune again!!

I am getting closer, I CAN FEEL IT!!! :)

Dan

 

[ol' smokey]

Your getting there. Did the autotune work on the next try? Let me know how the fan setup works. I have a Bradley that I put a 1200 watt finned heater strip in (no fan). This setup with the PID works great but I do have hot spots from grate level to another. A fan may just be the answer to that.

Here's a graph of the Bradley running at 130° this morning.

 

[dick foster]

I've already told you that autotune and trying to run a PID control loop will not work well with an actual fire and stoker fan.

This is simply because the size and therefore the heat output from a fire is variable over time. The heat output from it varies as to the size of the fire and the amount of fuel avaliable which varies as the fuel is consumed over time. Also changes in damper openings will vary the heat output from a fire as will changes due to weather etc.  

PID loops only work well where there are more or less constants involved such as the heat output from electrical heating elements that varies in direct proportion to the amount of power input into them and the responce is therefore somewhat predictible and can be planned and accounted for. A fire is in no way predictible to that extent.  

Running the fan with the relay output will also burn out the relay contacts in short order as it will be cycling on and off all too often.

Hook your fan up to the SSR you already have and set the contorller to run the SSR output with a simple on-off algorythm not a PID loop. If you want to use the relay output for something, use it for an alarm which is what it was desgined and engineering for and it's intended use.

 

[dick foster]

His application of a fan and yours are entirely different and I don't think either one of you really understand what a PID controller or a PID control loop really is, what they are designed to do or how they function.

All you need is a stir fan that keeps the temperature in your cook chamber even throughout it's volume all the time. In your smoker the fan should run constantly all the time though out the cook regardless of whether or not the heater has power applied. Therefore it needs no PID or any other controller for that matter. Maybe a door switch to stop the fan when you open the door.  

PID based systems are basically mathematical models of a closed loop control system that is used to effect the operation of a system by predicting and then applying a measured input based on measuring the output to effect a desired output behavior in a predictable and desired manner. How do you model a fire accurately over time where the fuel and oxygen vary? The short answer is you can't so a PID simply will not work nor can it be expected to work well.

In short like many things a PID controller is a tool that can be either understood and used well having good results or misunderstood and misused with poor results.

Better you should understand a little more about what it is you're trying to work with before proceeding further. If you don't, all that lies ahead is frustration and aggravation. The auto tune mechanism built into the controller is no substitute for what amounts to basic ignorance of the system and parts of it. It does however eliminate a lot of trial and error from trying to fine tune a system that was designed for a PID control loop in the first place. I have been there and so I know how tedious it can be.  A wood fire isn't something where a PID control system can be expected to work well. A gas fire with a control valve that changes the amount of fuel and therefore the heat output yes, an electric heating element yes, a wood fire no.    

http://en.wikipedia.org/wiki/PID_controller

http://motionsystemdesign.com/sensing-control/introduction_pid_control_0309/

Right now you're both reminding me of kids playing with loaded guns, only you're not likely to kill yourself or lose an appendage.   

 

[dick foster]

If you look, the answer in on the web. Weren't you paying attention in 7th grade science class? I know they covered it becasue I was paying attention and it was very long time ago for me.  

As to the autotune, see my replies below only read them this time. Apparently you haven't been reading the others.

 

[flyweed]

DIck...my fan IS wired to the SSR, and NOT the PID relay output.  Just because I am new to PIDS..doesnt mean I was born yesterday, and don't know jack chit about it.   I understand the concept and even have a Ranco temp controller this is a PID with simple on off configuration and a +\- degree adjustment that you can set from a 10 degree variation to within 1 degree on my fermentation equipment for home brew.  the controller kicks in a heating element that keeps the fermentation vessel warm and at a constant 65F

We are all here to learn something new and in this case it's about PID control.  I don't think we really need to be "scolded" in three seperate posts and told we are no better than 7th grade science kids.

since I am new to putting together my OWN PID setup, wiring it up and all....this is where all these questions stem from.   I apologize if this is a bit redundant and elementary for a seasoned PID veteran like yourself..but some of us have never built, nor set one of these up before and I THOUGHT that is what these forums were all about, helping each other out.

Dan

 

[dick foster]

You had said earlier you had it hooked to the relay output and you haven't said differently since.

I'm not scolding, I'm trying to teach you but it seems you are not reading the replies.. Like I said before, a PID loop isn't going to do you any good with a stoker fan and a real fire. There are simply too many variables to contend with. They do however work great with electric heaters and such. '

BTW I finally got the pics taken when I smoked a brisket this weekend and the email I promised is sent. Let me know if you don't get it. Some emails have trouble with attachments and there were several.  

 

[flyweed]

Cool...no autotune or PID setup..just a simple "stoker fan on at 225.....off at 230F would suffice nicely

I did however say I had the fan hooked up to the SSR..back in post 52:.

"I want to set the "PID" to turn the fan on at 325F and then off at say 335F...I figured a 10 degree difference would be good so it's not turning off and on all the time with too close of a degree difference.  Can you tell me the steps how to accomplish this..since I won't be using the Autotune...OR...since I do have my stoker fan hooked up to the SSR...will the autotune work just as well??"

Dan

 

[flyweed]

so after reading the manuals...I set the "SV" value for my temp of 225F  correct? any my Hy as 3? how do I set my hi and low or on and off points?

 

[justpassingthru]

Hey Dan,

I'm certainly not an expert or experienced with PIDs and when I checked out the links Dick posted they convinced me I'm a dummy!

However, I've installed my PID and I'm using it to control a electrical heating element in my GOSM, I cant' say if you can or can't turn your blower on or off with a PID, but here is how I understand my directions, hoping that yours will be similar and it will help you to understand.

First thing is the PID needs a starting point temp, then I needed to tell it how long it has to reach the target temp, then I needed to set the target temp and then I have to tell it how long to maintain the target temp.

In reading your posts you say you want to turn the blower on at 325° and then turn it off at 335°.

1. starting temp = 325°

2. time to reach target temp (let's say 10 minutes) = 10

3. target temp = 335°

4. holding time (let's say120 minutes) = 120

This is my programing formula, yours might be different:

Step 1. CO1=75° (starting temp lower than ambient)

Step 2. tO1=10 (minutes, time to reach target temp)

Step 3. CO2=110° (target temp)

Step 4. tO2=60 (minutes, holding time at target temp)

The CO1 and the tO1 etc., are displayed on the readout, all I do is enter the numbers.

On the front of your PID is the set button, when you push it once it what does the display read?

What does this button ">" do to the right of the set button, it might be used to change from temp to time.

The other two buttons must be used to increase of decrease the readout in the display.

What do the instructions say for changing temp and time, that is, what are the symbols used for temp and time?  On mine C is temp and t is time.

Personally, I'm just starting to understand the parameters section and "Hy" and I decided I'm not going to mess with it until I was able to program the on and offs, my thinking is to get it running and then fine tune it as I become more knowledgeable with how the controller reacts to my programing.

I hoped this has helped a little, I spent days reading the instructions before the light started to glimmer.

Gene

 

[justpassingthru]

Dan, bad news bro, I checked out your instruction manual, it says your controller is for a heating element, you need to disregard every thing I've told you, my controller is completely different than yours and while the principle might be the same they way I program mine is completely different. 

Here's what I understand from reading the manual:

Pg 3 #4. Parameter Setting

1. Press set

2. Press >

3. Press up or down to select parameters, what does that do?  Does it ask for numbers i.e., 325°?

It looks to me that Figure 3 on page 4 tells you how to program the parameters of the controller using info from Tables 1 & 2, looks like the only one that needs to be changed is #6 C° or F°

Turn controller on, push "set" insert code 0089 push set,

1st  parameter is "Inty" Table 1 says your controller is "default" to a PT100 temp sensor, that means it is already set

2nd parameter is "Outy" Table 1 says your controller is "default" 2 "Comment" note 1 on pg 4, meaning look at #2 on note 1, Relay J1 as alarm output...

3rd parameter is "Caty" Table 1 says your controller is "0" "Comment" note 2 on pg 4, Universal PID controller...

4th parameter is "PSb" Table 1 say your controller is "0" I'd leave it there

5th parameter is "RD" it is set to control heating

6th parameter is "CorF" change that to "1" for Fahrenheit

7th parameter is "End" push "set"

Pg 5,Table 3, I wouldn't mess with and it looks like Auto Tune only works after the high and low points have been set, please keep in mind, I say again I'm not an expert and this is just what I've gleaned from a quick perusal.

Were you not talking to someone earlier that told you what to buy, maybe he can tell you how to enter your temps to make it control a fan.

Gene

 

[flyweed]

just passingthrough...yes mine is completely different than yours, a bit simpler I think.  Dick has indeed been helping me, and has sent me some valuable info and photos of his setup.

I have done the "0089" setup menu already.  so everything is set there..and I did have to adjust the PSB setting from "0" to "5" as my unit was actually 5 degrees off. I have also adjusted the unit to Farenheit from Centigrade.  So that's all done..now I just need to set my temp where I want the fan to power on and the temp where it will power off.

Dan

 

[hughjass]

Hugh..good question.  If you are wanting to wire up a fan to a UDS..that is EXACTLY what I am doing.....you don't need one of those computer muffin fans...but you can buy a small 5cfm blower style fan from a chinese company  for about $6.00..I have the contact info.  It is the exact same 5v dc blower they use on "the stoker"

Dan

Hi Dan.  Do you still have the info for the 5v dc blower?  I'd like to start moving forward with this one.  Thanks in advance. :mug:
 

 

[flyweed]

yeah I do..the only thing I am unhappy with about it it took 3 weeks from China to get here..they ship for free...but man on man...it takes FOREVER!!!!

Here's a pic of my finished drum with pid....I used an electical junction box to mount the blower, so when I start the UDS up, I can just remove the top cap to let air flow freely into the drum to get it up to temp.

 

[dick foster]

That was a novel idea. I wonder does that thing move enough air for the smoker though. I have a 32 CFM muffin fan, 110VAC for simplicity but I do have a damper on it so I can adjust the flow down. I usually run it about half way but full open for a quicker warm up. 

 

[flyweed]

Dick..yes it was a novel idea....and it works great..at least today after I got my UDS started and settled down this little fan setup held my smoker at a solid 230F all afternoon, until I shut it down.

The fan moves 5CFM and is a 5vdc model.  It is the EXACT same fan they use for the commercial version called "the Stoker"  their smallest version of the stoker is also a 5CFM  5vdc model as well.

Dan

 

[garyt]

 I have been trying to get a PID controller working also, here is a link to it.   

http://www.lightobject.com/JLD612-Dual-Display-PID-Temperature-Controller-P43.aspx

I am having a problem with modulation at the start and end of when the fan starts and stops, I have a hy setting that isnt even in the manual, I also only want on and off control, it works but using either the built in relay or the SSR output I  seem to have some sort of pulse width modulation going on, any Idea on how to eliminate it or what the hy setting is.