Homeroasters - Home Roasting Coffee Community » DATALOGGERS - CONTROLLERS - RATE OF RISE METERS » Dataloggers/Controllers/Rate of Rise Meters
Who is here? 1 guest(s)
Page 2 of 2: 12
 Print Thread
TC4/Artisan showing "-1"
renatoa
Top  #26 Print Post
Posted on 03/22/2020 7:30 AM
It's normal to be an offset, but under the curve, not above.
"Normal" PID settings led either to undershot following, either to oscillating following, not permanently above.
Check your lookahead value, the graph above suggest you have a lookahead of some 30 seconds, or even more.
 
ROSTARN
Top  #27 Print Post
Posted on 03/22/2020 8:07 AM
Hi
I have the exact same problem! The arduino would freeze up and showing -1 on all channels.
https://forum.hom...wstart=120
My setup is drum roaster with ot1 electric heat, ot2 ac fan and io3 dc motor. I had it up and running stable for two years and recently had to replace the tc4 and tried the tc4+ as I had that extra integrated circuit separate before. Maybe the lcd took some damage at the same time?

I also did try switching out the arduino but it didnt help.

I did have some problems with my chinese 12v psu and after replacing that the issues became less frequent but still occured. I do have cheap chinese stuff for lcd screen and I2C and maybe that is what is causing this. I will try to remove mine, maybe it will help.

Let us know if the issue persist

Thanks for posting everyone!
 
jessep
Top  #28 Print Post
Posted on 03/23/2020 3:17 PM

Quote

renatoa wrote:

It's normal to be an offset, but under the curve, not above.
"Normal" PID settings led either to undershot following, either to oscillating following, not permanently above.
Check your lookahead value, the graph above suggest you have a lookahead of some 30 seconds, or even more.


Sure did, 57s for some reason. Thanks!

So, the lookahead is mainly there to align the BT with the background? Makes sense.
 
renatoa
Top  #29 Print Post
Posted on 03/23/2020 3:37 PM
Yes, but not for the whole profile, just for sections with a slope between certain limits.
Is the PID setup method of those too lazy to hunt for the perfect PID tuning. Is simpler to set I and D to zero, and P to whatever value, say 10, then appropriate value for lookahead, and be done.
In such scenario, if we assume the average power level would be, say 60%, in the Maillard (yellow) section, where profile allure is more important than for drying, and slope more constant, then the offset will be 60% / 10(P) = 6 degrees, value known as error in the PID source code.
For an average RoR having value 10 C degrees per minute, in the yellow section, 6 degrees means 36 seconds. Set this value for lookahead and you have a good enough following, without many headaches, at least for final part of profile.
And also, very important for some guys, no oscillations, so a more pleasant and smooth RoR than a hard to tune true PID.
Not so accurate for drying phase, where following is not so critical anyway.
 
Page 2 of 2: 12
Jump to Forum: