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

Mavrik said:

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.

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I'm a little late getting to the party on this one, but here we go....

As to "proportional", the MYPIN will not vary the voltage proportionally to a SSR.  An SSR sees a triggering voltage, which can be within a certain wide range, and it then flips "on" like a mechanical relay, just with no moving parts.  In essence it is a digital switch controlled by a DC triggering voltage.  In your post quoted above you are using a 3 to 32v DC triggered SSR so any voltage between 3 and 32 volts DC will give the same result.  The SSR triggers and the load on the output side is powered (the digital switch closes completing the power circuit).  3 volts does not give any different response than 32 volts so the value of the voltage is irrelevant as long as it is in the acceptable working range of 3 to 32v DC.

A PID is a three mode controller.  PID stands for proportional-integral-derivative,  and the three values are normally working in concert with each other to perform the desired function.  To just use a controller as  proportional mode only unit defeats the whole purpose of using a PID.  The output is generally either a static relay or a DC triggering voltage in 99% of the MYPIN's I've seen.  There is a way to manually set the proportional value if an auto-tune fails, but again the output is a either a static relay or DC triggering voltage.

If you are wanting a variable voltage output , it has to be a certain configuration MYPIN (output type code is "D"). Variable voltage will not work in concert with a SSR either. Variable voltage output MYPIN's are not that common, but they are out there. The most common will have SSR triggering output and/or static relay output.  What model do you have? (should be on the sticker - post the full model number and a photo of the sticker would be best).

Well, nevermind.  Looks like you figured it out. 

Hello to all......

I have not forgotten about this thread nor have I abandoned it.  I was offline for about a month when my motherboard died and I was traveling for work and just did not have time to reconstruct my PC.  Long story made short is the power supply fried, overvoltage arced through the MB and there was a hard crash that also killed my boot drive.  Now that the PC is rebuilt and all my data transferred over, I should be catching back up on my SMF reading this weekend (that's the plan).

A couple of you have sent me PM's during the time I was down. I think I have now answered them all, but if I missed one, please resend it.

Thanks

Thunderjosh said:

How low does your temp get before the fan turns on? At bbq comp I run 225 degrees, I fired my smoker with outside temp of 40 degrees and the fan runs constant till 221 degrees. Then pulses till 225 and shuts off. After it shuts off I hit temps 30-40 degrees over because it stoked the fire so long. I run 20 lbs of lump on start up. If I get it to start pulsing before the destination it may not over shoot as bad. I have a huge back woods clone that I just finished and trying to get tuned. And will the auto tune function work for me. I don't understand how it works.. Thanks Josh

 

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Slippin said:

 
Hi Thunderjosh,

On my setup the fan runs constant until desired temperature, I haven't played around with any of the PID functions. (I don't really think I need to)

The temp usually overshoots by 30ish degrees, however after 15-20min the temp comes down.

I don't cook in any competitions, so this isn't really a problem for me.

(I'm sorry if this doesn't help, most of this stuff is over my head.)

Good luck, and nice smoker! 

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Nice pit!   As to the overshoot, yes I would expect that.  Generally PID's are used to control electric elements which are instantly "off" when the SSR switches off (or starts to pulse the output as you noticed).  Fire in a charcoal/wood coal pit is not as forgiving.  I would try the autotune function and let it adjust the pit.  Might want to run without meat on the autotune session, but I would go with the normal load of fuel (both type and quantity) that you would use in a competition.   If the autotune can't quite figure out the slope of the way a fire in a pit responds to air flow, then you may need to tweak the settings for the P, the I, or the D (as in PID).  These are all adjustable in a MYPIN or Auber Instruments PID.  Like I said, in most builds, it's not necessary but we are dealing with a fire pit not a heating element.

I've never had to fiddle with the P, I, or D setting so you will be somewhat in uncharted waters, but I understand the principals involved.  Here is a basic chart of how the values and changes in them would interact on the process being controlled.  (but try the autotune first)

azbohunter said:

 
dward51,

Sorry to hear of your computer problems, when they work they are great and when they crash, well I don't even want to think of that!

I am one of those who contacted you after reading thread after thread on PID's. It was a bit intimidating for me at first (the build) but I am exceptionally pleased with the final product.

There is going to be a learning curve, I am well aware of that but so was the computer, and we all seem to have overcome that!

Any way, just wanted to say thanks for your help via PM's from this forum. Guys like you make life more fun for guys like me!

Dick

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Glad it's working. 

Thanks for the good words.  I'm not "the" expert, but I try to help where I can.....

Some additional info on SSR's in general, and how to select the correct model for DC Fans in a "power draft" on a smoker

There seems to be some confusion about SSR's and what device is needed for what application.  I'm going to take a stab at some basic info here that hopefully will help.

A SSR is a "Solid State Relay".  This is nothing more than a solid state (think transistor and/or computer chips) device that serves the same function as a mechanical relay.  That is, it switches a power to a load on or off. It does the same job as the good old mechanical or "dry contact" relay which is nothing more than a switch that is actuated by the application or removal of a control voltage.

The confusion seems to be when we start to talk about "triggering voltages" and "load voltages".

In most electric smokers, what you have is a PID that uses a SSR to switch a 110v or 220v heating element on and off based on the process temperature (pit temperature).  The confusion starts when you consider the PID outputs a DC triggering voltage to control a AC load voltage.  The low voltage and low amperage output of the PID does not power the load (heating element).  It only causes the SSR to change it's load side state.  An DC to AC SSR requires AC power on the load side of the device to work.  It's not like a DC mechanical relay that will click on and off with nothing connected on the load side of the mechanical relay.  SSR's require power on the load side to work.

SSR's have an advantage over mechanical relays as there are no moving parts, and no arcing across contacts.  If you have ever had a relay seize up in you car or home AC unit you know what I'm talking about.  In a mechanical relay, as the little contacts approach each other to close the "switch" in the relay, there is always some arcing between the contacts.  This will eventually cause the relay to fail.  The more you switch it on and off, the faster it will fail.  SSR's do not have this problem and are considered to be more reliable that mechanical relays.

The most common type of SSR we see is the DC to AC (DC triggering voltage from a PID controls an AC load voltage from an AC power source to the heating element or other AC load).  The Fotek 25amp models you see used in so many builds are of this type. 

However they also make DC to DC SSR's.  These models also use a DC triggering signal but they control (switch on/off) a DC load from a DC power source.  Some of you have been talking about building "power draft" control units where a PID is used to switch a fan on and off like the BBQ Guru units.  Since most of the small fans used in that application are DC powered, you need to have a DC to DC SSR.

• In the photo below, the SSR on the left is a DC to DC SSR.  This device would use the DC triggering output from a PID to switch a 5 to 60v DC load powered by an external DC power supply (not the PID).
• The SSR on the right is also a DC to DC SSR, but it has a higher voltage range for the DC load that is being switched.  This one will work with a load side DC power supply of 24 to 220v DC (again from an external DC power supply, and not the PID).
• In the Fotek models, the "DD" after the amperage rating (in this case 25 amps for both SSR's) signifies this is a DC to DC SSR.  The DC to AC models would show "DA" instead of "DD".

Here is the most common model we see in smoker builds.  It is a 25 amp, DC to AC SSR (DC triggering voltage from the PID which switches an AC load powered by an external AC power supply).


Hope this clears up the difference in load types and what type of SSR to use to make a power draft fan controller for a smoker.  (Note I have also see these exact same Fotek SSR's labeled as MYPIN SSR's, and these two seem to be the most common brands used by smoker controller builders).

Tim,

The PID only outputs a control signal and does not power a load.  You need a power supply feeding power to a SSR or relay (depends on what variation of the TA4 you have as to which).  The SSR or relay acts as a switch that is controlled by the PID (ie, flipped on or off).  The power supply through that "switch" is what powers your fan, heating element, or whatever else you have.

***Also if you have a SSR output PID and you connect a VOM across the load side terminals of a SSR with no load side voltage on the SSR, you will not see the SSR "close" the circuit when the PID triggers it.  It needs a load of some sort and voltage for the SSR to function.  This creates a feedback loop inside the SSR which is needed to make it work.  So don't panic if you have a SSR that does not seem to be working if all you have connected is a meter looking for continuity on the load side of the SSR.  If the LED on the SSR is coming on, try connecting voltage and a small load to the output side and it should work just fine (a small 120v lamp usually works for a PID & SSR that will be controlling a heating element).

In theory the SSR does the work of a plain old relay, but in actuality there is more to the equation to make the digital circuits inside the SSR work (it needs voltage and a small load to form the feedback loop).

Here is a diagram I made for another discussion with a forum member to help illustrate how the SSR works.  In his build, he controlled a outlet, but you can change that out for a heating element or other 110v load.  The key thing to remember is no power from the PID crosses over to the load side of a SSR at any time (the PID does not power the load).  There is no true "switch" inside a SSR as it's all digital logic circuits and no mechanical switch.  The concept of how the output side of the SSR performs is best illustrated by a "switch" though.