Temperature Control Box Build

[Loetz]

Ok, so I went back and played with it again now that the autotune is turned back on and I'm kind of getting a similar problem.

I set the set value to 51.5 and let it heat up to that temp. After that, the present value reads 51.5 for a long time. Then, once I change the SV, the the PV jumps up 52.2 and continues to climb. It's currently up to 53.5.

You can see this happen in the middle of my video here:

http://youtu.be/SAPQVwNdjV8?t=29s

This happened to me once during a mash and I was several degrees over what I should have been. It really ****** me off.

Edit: Sorry for the music on the video. There were some distracting background noises that I wanted to eliminate.

 

[Fil]

watched the vid ?????????????? WTF????????

ive used my pid a handful of times just to hit strike temp in my hlt and later sparge temps its a different make and ive not noticed it behaving like that.

i have noticed that my hlt when left to cool will 'stratify' in that the water is cooler at the bottom than it is at the top...

SO,,, if your test vessel is the same, AND you gave it a stir ??? when changing the settings??? then it may explain whats going on, but its a lot of ifs and ands

can you measure the temp with another device, or use the other pid to just monitor the temp ??

does it behave the same when upping the target temp rather than dropping it??

also are you probes in thermowels or naked in the vesel and if so are they watertight?

 

[Loetz]

if your test vessel is the same, AND you gave it a stir ??? when changing the settings???

No, I hadn't stirred it.

can you measure the temp with another device, or use the other pid to just monitor the temp ??

Yea, that's what I ended up having to do the last time, but that defeats the purpose of the PID.

does it behave the same when upping the target temp rather than dropping it??

It works fine when the SV is higher than the real temperature of the water. Even if it is only half a degree over the real temperature.

also are you probes in thermowels or naked in the vesel and if so are they watertight?

The probes are water tight.

Seriously, I'm at a loss here. Do any of you have any ideas? This is really frustrating since I've put so much time and money into this box and it's not working.

 

[Muddydisco]

To me all the problems lie in the pid itself, I noticed in the video that the SSr isn't actually on when the pid is climbing in temp. Have you tried the other Pid is it doing the same things?? If it is there must be some strange settings within it somewhere. if it's not doing same things throw it back to the supplier as faulty.

 

[Loetz]

The resolution on the video must be bad because the SSR is turning on when the PID is turning up the heat.
EDIT: Oh, now I see what you're talking about. I think that the PV is climbing because the heating element still has some residual heat that it's putting out after it was turned off.

Both PIDs are having this same problem. I've also tried swapping out the probes, but the problem remains the same. I imagine that there must be some setting someplace that needs to be changed, but I don't know what it would be. I suppose it's possible that all three of my probes are bad or that all of my PIDs are defective, but I don't really know. I'm hoping that's not the case.

Any other ideas?

 

[Muddydisco]

Have you got a manual for the settings for your pid?? if not could you please list down the options that you can see in the settings menu.
That way we can go through each one and check. I know it seems like going over something you might of looked at but there has to be something we are missing

 

[Loetz]

Here is a pdf of the manual for the Rex C100 PID Controller:
http://www.rkcinst.co.jp/english/pdf_ma ... zc21e1.pdf

When I go into the settings I get this:
Option -Setting- Explanation
AL1 -000.0- Alarm 1
ATU -0000- Auto-tune (set to 0001 to have it do an auto-tune)
P -12.3- Proportional Band
I -88- Integral Time
d -22- Derivative Time
AR -51- Anti Reset Wind-up
T -2- Heat Side Proportioning
SC -000.0- Temperature offset
LCK -1000- Set Data Lock

after the lock I get these options with these settings:

Option -Setting- Explanation
COD - 0000 - Change to 0001 or possibly 0002 to reach other menus
SL1 - 1000 - Input Type (1000 is for a PT100 thermocouple. Some PIDs use 1100 as the code for PT100)
SL2 - 0000 - Temperature Unit Type and Cooling Type
SL3 - 0000 - ????
SL4 - 0001 - Alarm 1 Type
SL5 - 0000 - Alarm 2 Type
SL6 - 0001 - Main Control Output Type
SL7 - 0000 - Excitation/non-excitation alarming
SL8 - 0000 - ????
SL9 - 0000 - ????
SL10 - 1001 - Run/Stop Function Setting
SL11 - 0000 - ????

Changing COD to 0001 brings up these options:
SLH - 100 - Setting Limiter High
SLL - 000.0 - Setting Limiter Low
PGdP - 3 - Place number of Decimal
oH - .2 - Differential Gap Setting
dF - 0 - Digital Filter Constant (When set to 1, it decreases the accuracy of the PV)

There are a few other parameters mentioned in the manual, but I don't see them in my settings menu.

 

[Baldbrewer]

Nah, as soon as you adjust the temp the ssr doesn't fire.
Don't forget we are dealing with temps here , not digital on /off.

Are you pids relay output or for ssr output?
Mine are for relay output so had to install separate dc supply for ssr coils. ( led driver off ebay )

 

[Loetz]

Nah, as soon as you adjust the temp the ssr doesn't fire.
Don't forget we are dealing with temps here , not digital on /off.

Ok, I adjusted the set value a few times in those videos. When are you talking about? I'm not really following.

Are you pids relay output or for ssr output?

They are SSR output. I'm sure of this.

 

[Baldbrewer]

40 secs in , the ssr doesn't fire when you adjust set point down.
But the probe temp rises .

My settings for relay NOT ssr

Aru 0000
P 0030
I 0240
d 0060
Ar 0025
r 0020
Sc0000
Lcy 0000

 

[Baldbrewer]

Cod 0000
Sl1 1000
Sl2 0000
Sl3 0000
Sl4 0000
Sl5 0000
Sl6 0001
Sl7 0000
Sl8 0000
Sl9 0000
Sl10 1001
Sl11 0000

Hope thes guide you a bit

 

[Baldbrewer]

This my pid model, :

 

[Fil]

referring to your online manual dbl check the LBd value is zero 0

otherwise it wont measure temps outside its alarms range ? see bottom of page 5 in the manual..

 

[Muddydisco]

Looking at his actual list he doesn't have LBA or LBD in there Fil?

 

[Baldbrewer]

Lbd is the deadband, it's in the manual not in his list.

 

[Loetz]

I don't seem to have lbd parameters in my settings. I don't think all of those parameters are available on all models of controllers.

Baldbrewer, the reason the temperature continues to rise in that video is because the heating element is still hot after it powered off. It's a heating overshoot problem. I compared our settings and tried changing my SL4 setting to zero like yours, but that didn't solve the problem.

Any other ideas?

 

[Fil]

Looking at his actual list he doesn't have LBA or LBD in there Fil?

spotted

DUH!!

sure its a typo but 1100 is the code for pt100 not 1000..

 

[Loetz]

Nope. The code for PT100 is 1000. I tried changing it to 1100 just to make sure, and it didn't work.

Any other ideas?

 

[Fil]

Nope. The code for PT100 is 1000. I tried changing it to 1100 just to make sure, and it didn't work.

Any other ideas?

just going by the table on page 7 of the manual?? 1000 is for s type thermocouple and 1100 for pt100??

you have 51 set for AR rather than the default 100 ??

and a possible conflict with alarm 1 with al1=0000 (off) but sl4= alarm 1 high deviation.. which may be forcing the LBA issue i looked at above, as the lba settings are turned off by the al1 setting but could be awakend by the conflicting sl4 value.. lovely lovely side effects...

as it also appears to have an out of the box initialisation phase, it might be worth looking at giving it a hard reset back to out the box status??

 

[Baldbrewer]

+1 on the pt100 code, mine is also 1000 not 1100 as stated in the manual :wha: