How to get one of those cheapo Rex C100 PIDs to work properl

EDIT:

This os a manual for the rec 100 that works for the chinese model.

http://style.oversubstance.net/wp-conte ... X-C100.pdf

Hello All,

I've seen a lot of people writing in frustration after buying a very cheap Rex C100. There is an official Japanese one which has a complete manual, this is about the clone/knock off version, which can be ordered on ebay, complete with a SSR for around a tenner.

This post is not about bypassing a rely to directly drive the SSR, nor is it about the SSRs themselves, more a record of all Ive managed to piece together having spent a large amount of time experimenting and googling how to get this little bundle of horror to work well. In the end, Ive learnt a lot more than I would have, were I to have bought a nice new sestos and had it work out of the box., so I am actually not too annoyed...

So. To sumarise, i got a Berme/RKG/whatever C100 complete with SSR and soon found that there is no decent documentation. Anywhere. It also came with a bit of a rubbish K thermocouple. I ordered some cheap 2wire PT100s, to use instead.

First of all, I mounted the 2 PIDs in an external waterproof box, with the SSRs on an aluminium sheet.



As you can see, i wired extension cables to the sensors. Its hard to see as this is all now installed, but I soldered these cables direct to the board, to avoid weak connections, which would alter the readings. I broke the plastic case out to allow the cables to poke trough too.



Now, once the PT100 cables are connected, to pins 8 and 9, i shorted pins 8 and 10... A three wire sensor might allow for automatic compensation for the overall wire resistance, but we can work around that later using the adjustment in the PID.

So this is where it got stressful. There are 2 menus, to adjust settings, one is accessed by holding the SET button for 2 seconds. This allows adjustment of the following settings...

AL1 - temperature at which alarm kicks in (my model has a res panel light, not function to connect to external sounder etc without a hack, not sure if even possible)
ArU - Autotune. 0000 is off. 0001 is on.
P - proportional band
I - Integral time
D - Derivative time
Ar - anti reset windup
R - heat side proportioning cycle
Sc - temperature sensor calibration (degrees C)
LcK - the lock on settings...

The above are all explained somewhere on wikipedia, so I will gloss over them...

The lock function is the just the pits. There are essential settings that need to be changed and they dont tell you the right codes. Easiest thing to remember - 1000 is 'god' mode, ie you can do anything. 0000 locks everything except the set value.

When you change LcK to 1000, exit settings menu, and press and hold shift and Set for 5 seconds. The screen pops up with Cod. On the top and 0000 on the bottom. Pressing set will scroll though the first set of options. Changing the value below to 0001 then pressing set will scroll through second set of options. These are the 2 'secret' menus.

The first set of options (cod set to 0000) are all SL1.. SL2 etc. the two that are of greatest interest are Sl1 and sl2. These are for the sensor type (pt100 ended up being set to 1000.) and temperature scale (in case you want to switch to farenheit).

The second set of options (cod set to 0001) are as follows.
SLH - set limiter high, the upper reading your sensor can detect
SLL - set limiter low the lowest reading it detects. I am not sur, but i think setting these right makes a difference to the accuracy and consistency of the readings. Dont quote me, but it got loads better after i adjusted these...
PGdP- number of decimal places, note not all sensors support decimal places
oH. Differential gap setting - still not sure what this does?
AH1 - alarm hysteresis - the number of degrees the pv has to drop below alarm level to switch off
dF - digital filtering. This is a terrible feature. It has a purpose of change the pv to match the sv, if its close. THIS MAKES THE PID TELL YOU LIES, SWITCH IT OFF (0000) AND LEAVE IT OFF!!!!!!

So those are the settings.....

Now, once you have set up the unit, made tweaks, changed sensor type etc etc, its time to calibrate, using real world physical processes. I asked my dad, who is a retired physics teacher, and for the level of accuracy we will achieve with our gear, he reckons we will be ok.

Calibrating to steam.

This test involves heating water to boiling in a conical flask on the hob. The sensors are dangled in the middle of the flask, and as the air is driven off by steam, the temperature will stabilise around 100 deg C



Go into your setting menu (hold set for 2 seconds) and click though to sc. this is the offset for how far the reading you get is from 100 degrees c. I have to adjust mine by around - 8deg c.

Now, when this is set, get some ice from the freezer, and level in a glass till most of it is melted. Due to the ice absorbing heat from the water, the water is always kept at just about melting temp, or 0 deg C. Make sure the sensor is floating in the water but not touching the ice, which will actually be colder than 0 deg C.



If you've got it right, the water should read around zero...


Result!

If boiling and freezing point are accurately set, then all temperature in between should be pretty darn close. Now you can mash with confidence!

I hope this helps you all. However the is one final step! Go into settings and set LCK to 0000, so the only changeable value is the set value, we don't want to go and mess up all our work, do we?

Further reading....

https://mightyohm.com/forum/viewtopic.php?f=10&t=328

These guys seem to be using these to control sous-vide cookers made from burco boilers, but the issues they face seem the same as ours!

Have fun,

Rob

Thanks for the informative post

I will be making reference to this soon as I want to set up my two PID's for my new setup, I have previously used a PID but it was a while ago and I have been putting off setting them up as I forgot how to do this.

One thing I was wondering is that I want to use my PID's to control my HLT and boiler. Both have two 300kw elements, if I get a big enough SSR can I run both elements through the one PID or need a PID for each element?

A great how to. Certainly will clear things up for those using the Rex version.

Thanks for the informative post

I will be making reference to this soon as I want to set up my two PID's for my new setup, I have previously used a PID but it was a while ago and I have been putting off setting them up as I forgot how to do this.

One thing I was wondering is that I want to use my PID's to control my HLT and boiler. Both have two 300kw elements, if I get a big enough SSR can I run both elements through the one PID or need a PID for each element?

Good question. Power in watts is current (amps) x voltage, so a 3000 watt element would need (3000/240) is 12.5 amps. If you can delivery a safe 25 amps to a 40a SSR, and it is well heat sinked, My guess is that it would be ok, but please don't do this without checking the full system and quality of all components, cooling and wiring!

You could use both elements in the hlt to get it near to needed temperature, and manually switch off the second, leaving single element maintain the temperature. Btw, why do you need PID control of the boiler. Just get it boiling!

In answer to the original question though - one pid per process, you may need an additional SSR to manage the current...

Hope this helps

You just need to autotune it now.

Cheers for that will have to dig my c100 out and have another play, I couldn't get it to switch to p-100 from K type last time I played with it.

Thanks for the informative post

I will be making reference to this soon as I want to set up my two PID's for my new setup, I have previously used a PID but it was a while ago and I have been putting off setting them up as I forgot how to do this.

One thing I was wondering is that I want to use my PID's to control my HLT and boiler. Both have two 300kw elements, if I get a big enough SSR can I run both elements through the one PID or need a PID for each element?

Good question. Power in watts is current (amps) x voltage, so a 3000 watt element would need (3000/240) is 12.5 amps. If you can delivery a safe 25 amps to a 40a SSR, and it is well heat sinked, My guess is that it would be ok, but please don't do this without checking the full system and quality of all components, cooling and wiring!

You could use both elements in the hlt to get it near to needed temperature, and manually switch off the second, leaving single element maintain the temperature. Btw, why do you need PID control of the boiler. Just get it boiling!

In answer to the original question though - one pid per process, you may need an additional SSR to manage the current...

Hope this helps

Thanks yes that makes sense, I will be sure to buy decent quality SSR's not the cheapo ones you get "free" with the PID's

I want a PID for HLT and boiler so that I can brew in the evenings. If I fill up my HLT in the morning before work and set it for say 60c then when I get back from work it will be nearly ready for mashing straight away. With doing 1BBL batches there is at least 2 hours wasted on a brewday just waiting for the HLT to get up to temp!

For the boiler I find that with two elements its either boiling too vigorously or not enough so I am constantly turning on/off one of the elements throughout the boil. If I had a PID to control it would do all the work for me and save me constantly watching the boiler. I have had a few close calls with boil overs so hopefully this will sort out this problem.

It just means the process is just that little bit more automated and easier for me so I can concetrate on other things and not having to watch the boiler the whole time

Thanks for the informative post

I will be making reference to this soon as I want to set up my two PID's for my new setup, I have previously used a PID but it was a while ago and I have been putting off setting them up as I forgot how to do this.

One thing I was wondering is that I want to use my PID's to control my HLT and boiler. Both have two 300kw elements, if I get a big enough SSR can I run both elements through the one PID or need a PID for each element?

Good question. Power in watts is current (amps) x voltage, so a 3000 watt element would need (3000/240) is 12.5 amps. If you can delivery a safe 25 amps to a 40a SSR, and it is well heat sinked, My guess is that it would be ok, but please don't do this without checking the full system and quality of all components, cooling and wiring!

You could use both elements in the hlt to get it near to needed temperature, and manually switch off the second, leaving single element maintain the temperature. Btw, why do you need PID control of the boiler. Just get it boiling!

In answer to the original question though - one pid per process, you may need an additional SSR to manage the current...

Hope this helps

Thanks yes that makes sense, I will be sure to buy decent quality SSR's not the cheapo ones you get "free" with the PID's

I want a PID for HLT and boiler so that I can brew in the evenings. If I fill up my HLT in the morning before work and set it for say 60c then when I get back from work it will be nearly ready for mashing straight away. With doing 1BBL batches there is at least 2 hours wasted on a brewday just waiting for the HLT to get up to temp!

For the boiler I find that with two elements its either boiling too vigorously or not enough so I am constantly turning on/off one of the elements throughout the boil. If I had a PID to control it would do all the work for me and save me constantly watching the boiler. I have had a few close calls with boil overs so hopefully this will sort out this problem.

It just means the process is just that little bit more automated and easier for me so I can concetrate on other things and not having to watch the boiler the whole time

A PID is not going to be able to control a boiler properly as you will set it to 100c and then leave it. You need a controller of some kind that will alter the duty cycle so you can set it with just enough power to keep a rolling boil. I use one I made up from bits off eBay for something else where I control an element which I turn down to around 1000w when boiling.
IIRC a light dimmer switch works on the same principles but obviously can not handle the voltage

You can set some PIDs to control duty cycle rather than temp.
The Sestos can be put into manual mode by holding the down button which is useful otherwise a dimmer or some other PWM controller with a 240v SSR would work.

Thanks for the informative post

I will be making reference to this soon as I want to set up my two PID's for my new setup, I have previously used a PID but it was a while ago and I have been putting off setting them up as I forgot how to do this.

One thing I was wondering is that I want to use my PID's to control my HLT and boiler. Both have two 300kw elements, if I get a big enough SSR can I run both elements through the one PID or need a PID for each element?

Good question. Power in watts is current (amps) x voltage, so a 3000 watt element would need (3000/240) is 12.5 amps. If you can delivery a safe 25 amps to a 40a SSR, and it is well heat sinked, My guess is that it would be ok, but please don't do this without checking the full system and quality of all components, cooling and wiring!

You could use both elements in the hlt to get it near to needed temperature, and manually switch off the second, leaving single element maintain the temperature. Btw, why do you need PID control of the boiler. Just get it boiling!

In answer to the original question though - one pid per process, you may need an additional SSR to manage the current...

Hope this helps

Thanks yes that makes sense, I will be sure to buy decent quality SSR's not the cheapo ones you get "free" with the PID's

I want a PID for HLT and boiler so that I can brew in the evenings. If I fill up my HLT in the morning before work and set it for say 60c then when I get back from work it will be nearly ready for mashing straight away. With doing 1BBL batches there is at least 2 hours wasted on a brewday just waiting for the HLT to get up to temp!

For the boiler I find that with two elements its either boiling too vigorously or not enough so I am constantly turning on/off one of the elements throughout the boil. If I had a PID to control it would do all the work for me and save me constantly watching the boiler. I have had a few close calls with boil overs so hopefully this will sort out this problem.

It just means the process is just that little bit more automated and easier for me so I can concetrate on other things and not having to watch the boiler the whole time

A PID is not going to be able to control a boiler properly as you will set it to 100c and then leave it. You need a controller of some kind that will alter the duty cycle so you can set it with just enough power to keep a rolling boil. I use one I made up from bits off eBay for something else where I control an element which I turn down to around 1000w when boiling.
IIRC a light dimmer switch works on the same principles but obviously can not handle the voltage

This is an interesting point. A properly set up PID however, will reduce hysteresis by maintaining cycling on and off at a rate which maintains an input of energy equal to that being lost by the system. Stability is maintained when a balance is kept between these two factors.

Now, as the boiling point of water is 100 deg C (temperature of Steam at 1 atm pressure at sea level), in theory, the PID sensor would show that the boiler is running at 100 deg. C only when the water in the boiler is actually steam, so a rolling boil may well show the temperature of the water in the boiler at less than 100Deg C. In fact, a rolling boil and a gentle simmer may read at different temperatures. As the temperature increases towards boiling, the heat lost in the system also increases as does the rate of evaporation, keeping it below 100 deg C.

To complicate matters, we are not boiling water, but rather wort. The concentration of the wort also changes during the boil and as a result, the temperature it will boil at will vary slightly.

All of this theory is great, in theory, but I would be very interested to know whether or not a rolling boil can be maintained consistently using a PID. I would personally expect that a PID would possibly work in this instance, but I would rather bow to those who have tried and tested experience of using one for this purpose and who can report back.

Incidetally, I'm building my boiler at the moment, and it has 2 x 2000Kw elements. I plan to use both to raise to the boil, and maintain the roll with the other - its s 33l SS stock pot, just buy unplugging the second element when its up and running. My old plastic boiler was a BRUHEAT one and did in fact have a thermostat, which clicked on and off, when the temp was limited - this worked fine for a simmer and prevented boil overs, but I always cranked it up for a rigorous boil.

I found it!!!!!!!!!!

The manual that actually works with my pid!

http://style.oversubstance.net/wp-conte ... X-C100.pdf

Enjoy peeps!

Finally got around to trying this.
First obstacle:
Cant get Lck to 1000, 255 is max, selecting 4th digit will go from 0000 to 0255.
Aru is stuck at 0000 can't change it.

Given up on it as it is a POS.

When it is set to 255, is anything unlocked?

With it set to 255, I can't get to the 2nd menu, shift/set does nothing.

Does the info on this page help?

http://www.instructables.com/community/ ... -settings/

With it set to 255, I can't get to the 2nd menu, shift/set does nothing.

Hi Hairybiker.

It appears there are some fundamental differences in how yours operates, compared with mine. There are four digits, which control locks. On mine, the first locks the hidden menus (0 is locked, 1 is unlocked) The second digit locks the SV, the third locks the alarms, the fourth the non hidden settings other than SV and alarms. Could you check if this works. Also, make sure you hold set for a couple of seconds after changing, before pressing and holding set and shift together for 5s.

Maybe the answer will come from what happens after this.

Rob

Just one other thing, I have a manual here that recomends 0100 for secret menus, which it calls initialisation mode.

and another that says 0000.

Tried 0001,0010,0100,255,0110,0111,0011

can't get into the set/shift menu

One other number 0089?

Just seen that banded around too.

Rob

PS - I love a challenge.... If you're throwing it out, send it to me, I hate unsolved mysteries, I'll paypal yo the postage if you want...

I'm really sorry to go over this - but a really common mistake is to not press set after changing the LCK number, you need to press Shift and Set together after switching back to PV/SV mode, otherwise it doesn't matter what lock code you have. I'm sure you've read this, but just on the off chance you missed it...

Again, sorry if this isn't helpful, just breaking down every possible thing it may be, really hope this is helpful....

I found you NEED to press set to return to the main display anyway, so always do.

Just tried 0089 same as above.

I will use it on my hlt with the k type.

I found you NEED to press set to return to the main display anyway, so always do.

Just tried 0089 same as above.

I will use it on my hlt with the k type.

Hi again...

This has been bothering me. (I said I like a challenge...) One thing especially... I can only adjust the values in each column to 0 or 1 on my unit. To my mind, the four digit value is in binary, which would make sense, as it generates a unique value for each combination, and this means complex variations of one or zero createsa unique value to be sent to the logic board. What if the interface on your model had been erroneously set to decimal values (256 variants, 0-255), many of which would be useless, but some of which correspond to the decimal...

This would make the following binary numbers correspond to the respective values. Byt this logic, 1000 in binary would be 0008 in decimal, I think it might just be worth a try, and certainly worth trying 0000 to 0015! (just a thought).

Rob

0000=0
0001=1
0010=2
0011=3
0100=4
0101=5
0110=6
0111=7
1000=8
1001=9
1010=10
1011=11
1100=12
1101=13
1110=14
1111=15

IT switched to 255 when I pressed up on the 4th digit, the rest do cycle in decimal, eg 39 to 40. Will try out the idea later, brewing my inaugural brew on my new Grainfather at the mo.