MYPIN TA4 PID manual, programming instructions and general PID/SSR info - by request

Discussion in 'Smoker Builds' started by dward51, Sep 15, 2013.

  1. dward51

    dward51 Master of the Pit OTBS Member

    Slippin,

    Sorry I apparently missed your original question post.  Guess I got distracted by what appeared to be a dangerous wiring job in another one just prior to yours.

    Looks like you solved the issue though.
     
    Last edited: Jan 18, 2014
  2. dward51

    dward51 Master of the Pit OTBS Member

    That is so cool.  First time I've seen a PID in a home-brew application of a power draft clone. Great idea though.

    And dude, turn up the heat!  67 degrees in the kitchen?  My wife would shoot me (she was saying it was cold in here a little while ago and it's 74).
     
  3. Thanks Dward!

    67 degrees here in Wisconsin is nice and toasty! [​IMG]

    Smoked some ribs using the PID fan controller and they turned out great!

     
  4. btberlin

    btberlin Newbie

    If you Google" PID controller PV"  you will find a wikipedia article that explains how PID controllers work.  Here is a small snip from the explanation about PV, which is the value that changes rapidly when you press the set key on thr MyPin controller.

    process variableprocess value  or process parameter  is the current status of a process under control. An example of this would be the temperature of a furnace. The current temperature is called the process variable, while the desired temperature is known as the set-point.

    Measurement of process variables are important in controlling  a process. The process variable is a dynamic feature of the process which may change rapidly. Accurate measurement of process variables is important for the maintenance of accuracy in a process. There are four commonly measured variables which affect chemical and physical process: pressure,temperature, level and flow.

    Next is suppose you would want to know what the value of knowing the size of the process value is - that is, what the point of displaying it is.  That, unfortunately, I cannot answer.  :)

    b
     
  5. dward51

    dward51 Master of the Pit OTBS Member

    When using a PID with a temperature sensor, the PV or "process value" is the temperature measured.  The "set point value" is the desired temperature you want the controller to maintain by controlling a heat source.

    The reason it's called "process" value in industrial applications is you may be measuring other things than temperature.  Examples are pressure, flow rate, rpm, etc....  PID stands for "Proportional Interval Derivative" controller.  Translated more closely to English, that means it's an electronic device that uses algorithms (math) to calculate the error or difference between a process value and a set point value (what it currently is compared to what you want it to be) and then takes some action to reduce the calculated error by controlling an external function.  If you can measure something with a sensor, you can use a PID device to control an external force acting on what you are measuring.  It may be turning on/off a heating element like we do in a smoker, opening/closing a valve in a micro-brewery, etc....

    Some processes need to be tracked closely, which is why you have digital displays.  The temperature point we need to maintain in a smoker is not as critical as most industrial applications and a PID is really overkill for what we need.  But they are so inexpensive and do work well.  As to how close a set point is maintained, that depends on the device acting on the process (heating element) and the programing values input into the algorithm in the PID controller. 
     
    Last edited: Jan 25, 2014
  6. btberlin

    btberlin Newbie

    I'm afraid I am not convinced by your explanation, so perhaps you can clarify better.  On the MyPin  TA4 controller, there is a large digital display of the measured temperature, which you are describing as the process value or PV.  What was questioned in the part of this thread that I replied to, was what the rapidly changing value is - the one that appears when you press the "set" button, to toggle the lower display from the set value.  That row of LEDs is labeled SV/PV.  If, as you describe, the PV, or rapidly changing value is the instantaneous state of the process being controlled, the explanation is not at all consistent with what is seen - which is a rapidly changing value that changes with the rightmost digit of the displayed value, but whose values are ranging from "0" to perhaps "10" or so.  My measured value (right now a water bath for a rye sour starter) is in the range of 72-75 deg F, and the PV is all over the place from 0 to 10, as I mentioned.

    bert
     
  7. btberlin

    btberlin Newbie

    I am actually reading the legend on the front of the controller incorrectly.  The "PV" legend is meant to be for the row of large LEDs above the legend, and the "SV" legend for the row of smaller LED's below.  So, yes, the PV is the process variable, or in my case the temperature at the TC.  However, that was not what the original question was about.  When you press the set button, the SV row toggles between the value that you want the controlled process to reach, and a rapidly changing display that looks more like an error value.  That rapidly changing value is what the original poster was interested in.  I would assume it somehow represents the error between the set value and the process variable value.  I did notice that when it is occasionally "0" the last digit of the PV doesn't change.  Or so it seems.

    bert
     
  8. dward51

    dward51 Master of the Pit OTBS Member

    Pushing the SET button will toggle between the "normal" PV/SV display and PV/OUTPUT display.  You are correct that this gives you a visual representation of the error the unit is calculating and "0" is at set point.  As to what useful function this optional display mode serves, I can't answer that one either.  I'm sure there is some need for it in one industry or another or they would not have put it there.  I know there is a way to force a TA4 into a manual "duty cycle" timed switching mode and I think it comes into play there but I have never tried that.
     
  9. dward51

    dward51 Master of the Pit OTBS Member

    Also the fellow who made the best English MYPIN manual I've seen, recently released an updated version of the manual.  Revised in November 2013.  Main revision is he added a summary of what the default setting should be for most temperature controlling setups on page 15.  It shows what user needs to change and what should be left alone.
     
  10. mavrik

    mavrik Newbie

    I would like some help with the mypin controller. I want to run this on proportional, in other words, the voltage output varies with the demand. I'm using a 3-32DCV SSR. I'm not sure what the controller settings should be, but here is the current settings that seem relevant, most are controller default.

    PUF 0.0
    P 33
    I 24
    d 0.04
    hys 100
    ctl 001 also tried on 020

    The voltage to the SSR is aways around 1V no matter on the demand. The second SV number (I assume this is the proportional % output) does change, OUT1 flashes like it's is delivering proportional. It looks like it's working but without voltage output to the the SSR.
     
  11. invictaslave

    invictaslave Newbie

    hey guys,

    I have a mypinTA4 and yes the 3 and 4 terminal on the paperwork is fliped from the actual PID but anyway I found that out after a frusterating trouble shoot

    anyway my question is when I set my pid to a certain temp say 200 degrees the PID fires the SSrelay just fine for the first 140 degrees and then it flickers on and off for a good hour befor reaching its programmed temp of 200 and does not acually stop at the 200 degrees it goes over about 4 degrees and continues to flicker and slowly raises the temp  any thoughts?

    invictaslave
     
  12. mavrik

    mavrik Newbie

    The hysteresis is too high invictaslave.
     
  13. btberlin

    btberlin Newbie

    I think that taking a look at the Wikipedia article about PID controllers may help you understand better.  

    The SSR is NOT a proportional device - it is like a binary switch which is either on or off.  Once the on threshold voltage is reached on an SSR, on the control side, the switched side, which is switching the 120 VAC to your heater is on.  Period.  What is proportional is the TIME that the SSR stays on, and that is controlled by taking into account past, present and probable future deviations of the output from the set value.  So, what you as a user will notice is that well below the set point temperature, the SSR switches ON the heater.  AS it gets closer to the set point temp, it starts to pulse the heater, on-off-on-off and so on.  When the set point is reached, it may continue to pulse depending on various factors and settings.  For example, there is hysteresis, which is an intentional zone of delay in temperature control, so that the SSR doesn't "bounce" on and off rapidly.  YOur best bet is to set the desired temperature, and press the button to turn on the learning mode, and let the controller decide how best to control the setup- it will account for past, present and likely future errors depending on how fast the heater heats up, the thermal mass of the heated mass and so on, and will likely come up with the best settings.  

    One other thing - i had a MyPin pid and type K TC, in which the displayed temp drifted significantly.  I wrote to the manufacturer's rep via AliBaba, and they indicated that it was not an unexpected thing with K thermocouples.  Her advice, to rule out the PID itself, was to short the input for the thermocouple with a piece of wire.  That should produce a steady temp display.  I haven't tried it, as the vendor i purchased from via Amazon took the problem as a PID problem, and refunded my money, and I purchased a different unit which is more steady.  But for anyone reading this thread who is experiencing drifting temperature display, say, in an ice-water bath, try the trick of shorting the TC terminals on the PID to see if it is the PID or the TC.

    bert
     
  14. btberlin

    btberlin Newbie

    To Mavrik - additional info - add to my last post a few minutes ago.  This is from Wikipedia:

    solid-state relay (SSR)  is an electronic switching device that switches states when an external voltage is applied along its n-type and p-type junctions. SSR has a small control signal that controls a larger load current or voltage. It consists of a sensor which responds to an appropriate input (control signal), a solid-state electronic switching device which switches power to the load circuitry, and some coupling mechanism to enable the control signal to activate this switch without mechanical parts. The relay  may be designed to switch either AC or DC to the load. It serves the same function as an electromechanical relay, but has no moving parts.

    I underlined and bolded the relevant parts for emphasis.

    b
     
  15. mavrik

    mavrik Newbie

    Sorry my terminology is incorrect. That is fine if it times on/off instead of variable voltage. But right now it's not doing either, that is the largest issue.
     
  16. btberlin

    btberlin Newbie

    Mavrik

    Sorry - i misunderstood what you were getting at.  If I recall correctly (I am not at home, and can't check directly), the AL1 output is also a low-voltage control output that would trigger an SSR.  So, you could hook the SSR to that temporarily and see if it fires when the set point is exceeded.  Make the setpoint let's say 20 degrees  below ambient so the AL1 lamp lights.  If the SSR does trigger, then there is a problem with the ssr output.  If it doesn't, either the ssr (which as I recall is polarized on the control side) is defective or the PID is defective.  You could, I suppose, try to fire the SSR with a couple of 1.5V batteries in series, which should reach the fire threshold for the SSR.

    One question i would always ask, as a support engineer - did this setup EVER work? and stop working at some point?  Or is this a new setup for you?  If it did work at one time, walk back to the point at which it worked, and see what changed.  If not, and you bought the MyPin, say from Amazon, you should be able to get your money back and buy a replacement.

    Hope this helps.

    Bert
     
  17. handymanstan

    handymanstan Smoking Fanatic Group Lead

    When the temp gets to about 180 and it is set to 200 hit auto tune and that should fix it. 

    Stan
     
  18. mavrik

    mavrik Newbie

    On mine (TA7) the AL1 is a relay contact. I need the proportional control, so using the AL1 relay won't help. This is a new install. What I would like to know if someone has this running, what is your voltage of the 'out1 SSR'?
     
  19. btberlin

    btberlin Newbie

    Mavrik - I also suggested using a couple of batteries in series to trigger the SSR, just to try to isolate the problem.  If you can do that, disconnect the control side of the SSR, and connect a battery source (check the specification for the on voltage for the SSR - you need to apply that to the control side to turn the load side "on.") you should be able to isolate the failure as either the PID or the SSR.  Also, i suggested the AL1 output as a diagostic "trick," not to use it for controlling the load.  I believe, given the triggering range for the SSR, that hooking it up to the AL1 output would trigger the SSR - again, just as a diagnostic step, not to use the AL1 output for controlling your heater.  Which SSR are you using? Did it come with a spec sheet? What is the "on" voltage on the control side?

    I am away from home until March 5, so if you get no answer before then, and are still working on this project, I can measure the "on" voltage at the SSR control terminals on my PID.  In the meanwhile, if you try one of the ideas above, you may be able to diagnose the problem on your own.

    bert
     
  20. mavrik

    mavrik Newbie

    I found the problem; There was no contact between the inside circuit board to the outside terminals to 'out1 ssr'. I filed and put some goo on the inside clip. Now it works like a champ.
     

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