REX-C100 PID (cheapest PID on ebay)

[Walker]

These PIDs have been discussed on here recently in several threads because they cost so little. You can literally find these for $0.99 and free shipping in auctions on ebay.

The auction listings are always misleading (meaning "false") in that they indicate that they have a 12V pulse output suitable for driving an SSR. There are models of the REX-C100 that do have the SSR output, but I have never seen anyone selling them on ebay. All of the ebay ones have a mechanical relay output and not an SSR control output.

They also usually have "F/C" in the title, which can lead you to believe that they display in either Fahrenheit or Celsius. Not true. They only do Celsius.

A friend of mine bought one of these after falling for the false advertising. Not only was the product equipped with a relay output and displayed Celsius only, but it also was broken. The temp probe input (K-type thermocouple only) has some sort of problem. With no probe connected, it reads about 3000*C. With a temp probe connected, it reads "EEEE".

Long story short, the ebay seller was a ********* and would only refund half of his money AFTER my friend left POSITIVE FEEDBACK. My friend just gave me the PID to play with.

I popped the case on that thing open last night to see if I could figure out what was wrong with the temp input. I didn't see anything obvious, and I didn't have time to really tinker with it, but I did realize as I looked at it that this thing can EASILY be hacked to make it drive an SSR.

There is a small relay soldered down near the output terminals. There are a couple of voltage controllers on the board, one delivering 12VDC and one delivering 5VDC. I couldn't tell which one of those supplies ended up ultimately feeding to the relay control coil, but it's irrelevant. The point is that the relay is receiving a DC control signal to activate it, and that signal is either 5V or 12V.

Most SSRs that I have seen require a control signal between 3VDC and 32VDC, so 5 and 12 are perfect.

So... with a couple of wires and a soldering gun, you could tap onto the bult-in relay's control signal and bring those wires out of the controller. Connect them to an SSR. Done.

The internal relay would still be clicking and clacking, which isn't great for it, but the good news is that if the relay ever died, you wouldn't even care or notice.

A cleaner solution would be to actually remove the built in relay and jumper the signals that are used to control the coil straight to the output terminals that used to be switched by the relay. Then you wouldn't even need the extra wires coming out of the back of the PID for the SSR. You could just use the screw-down terminals that are on the back.

I *really* want to try this out as an experiment, but since the REX-C100 I have is busted, I can't do it. I am going to try and snag one of the $0.99+free shipping PIDs off ebay to see if I can do this and have it work well.

Alternately:
If anyone bought one of these and got stuck with it, and if you don't want it, PM me. I would like to hack that thing and would be willing to pay a tiny bit for something that you might be considering as junk.

 

[betadave]

I tried the conversion of the c100 to SSR output. I opened the unit, found two holes somehow intended for a diode and soldered two wires to the 12 volt signal to the relay (rated for 10 amps, by the way) and ran the wires out the back. Setting the P to the default 30 and plugging it in, it ran just as suggested.

It is true the ad on eBay is deceptive. it says SSR and it implies F but it is not there. The vendor offered a $10 refund on a $18 purchase so I have a functional unit for $8. There is no adjustment for the duty cycle for SSR but the relay setup is just fine.

I did not see $.99 and free shipping or I would have gotten that. If I do spot such a deal, I will pounce on it as that would be the cheapest PID controller in the world. If you decide to get one of these, expect to dispute the sale through eBay. If you get one for $18 like me, the seller will offer you $8 but hold out for a complete return since you wanted SSR output and didn't get it. The seller will come back with $10. That is where I just accepted the deal. Maybe you can do even better? If you have never had a dispute through eBay, do not click the problem resolved button until you have the money back in PayPal. I did it early and it took special calls and got "scolded" twice for being a dummy from the folks at eBay.

Also, the instructions that come with this are great if you can read chinese. I did find a good complete set in English with a google search of REX C100 so i was saved from having to learn a new language.

 

[rod734]

I bought one of these and according to the instruction manual it has a 0-12 volt ssr relay output.

After studying the instruction manual more, I don't think it does have an ssr out. The model no, has letters after the C100 that you have to match up to a legend to see what features you actually have. I think I can still make to work with an old cell phone charger to trigger my ssr and then switch over to my PWM to controll the boil. I'm still waiting on my SSR and heat sink to put this thing together and try it. I'll probably have one of the instructors at school look at the design in case I'v overlooked something.

 

[Walker]

I bought one of these and according to the instruction manual it has a 0-12 volt ssr relay output.

After studying the instruction manual more, I don't think it does have an ssr out. The model no, has letters after the C100 that you have to match up to a legend to see what features you actually have. I think I can still make to work with an old cell phone charger to trigger my ssr and then switch over to my PWM to controll the boil. I'm still waiting on my SSR and heat sink to put this thing together and try it. I'll probably have one of the instructors at school look at the design in case I'v overlooked something.

If you got it off ebay, it does not have SSR output. I can 99.99% guarantee you of that.

The phone charger through the built in relay will work to drive the SSR, but I don't know how long it will last for you. For a HERMS or RIMS system, the thing will be turning on and off pretty rapidly. The relay will eventually crap out.

Earlier I made a claim that these could be found for $0.99 and free shipping on ebay. And, indeed, at that time I had ebay watches on no less than 10 of them for that price. I let the first couple go past with winning bids between $2 and $3. Then suddenly, all of those auctions I was watching were yanked down.

I can't find them for $0.99 and free shipping anymore.

 

[rod734]

The relay will not be switching thet much untill I switch to the pwm to controll th boil. I will run it in auto mode like a thermostat through my mash, and ramp it up to 212f then go to the pwm once it starts boiling. I wouldn't think that would any harder on the relay than a pwm only. I'm also going to build another pwm in case of some kind of electrical failure on brewsay.
I may go in side the pid and see how much voltage is switching the 220 relay and use it if if it is what I can use for the ssr.
I'v been watching those cheap pids on ebay for weeks and bid on probobly 50 up to $12 trying to get one for less than $18 and always got outbid in the last seconds. I think it's rigged.

 

[Walker]

I am not talking about the SSR when I say "relay". I am talking about the mechanical one built into the PID that you are going to run your DC power through.

 

[Brewing Clamper]

Yeah, I got hosed by one of these. I haven't even installed it or anything. First off, I ended up with the 240V version for some reason. And no, there is no ssr output. I haven't had time to deal with the problem resolution thing on ebay, but it may not be a bad idea... any way of getting this thing to work with 120v? I can't imagine it actually uses that kind of juice!

 

[Walker]

Yeah, I got hosed by one of these. I haven't even installed it or anything. First off, I ended up with the 240V version for some reason. And no, there is no ssr output. I haven't had time to deal with the problem resolution thing on ebay, but it may not be a bad idea... any way of getting this thing to work with 120v? I can't imagine it actually uses that kind of juice!

The PID actually runs on anything from 90VAC to 250VAC. It will work fine on 110V.

 

[Brewing Clamper]

Really? cuz I couldn't get it to power up!

 

[Walker]

Then you probably have a busted one.

 

[rod734]

I am not talking about the SSR when I say "relay". I am talking about the mechanical one built into the PID that you are going to run your DC power through.

OK I see. I wasn't aiming to run DC through it, I was just going to come off one leg of the 220 out to run a DC power supply of some type. Switching a power supply off and on a lot may cause it to fail soon. I don't have any idea how rugged the relays are, but it said on the listing for uses was as a kiln controller. I guiss I will do a performance study and let others that might be thinking about going for the cheap one know what they are in for. Im not an electronics man, just a tinkerer, so Im all ears if you have any ideas.

 

[Walker]

I think you might be misunderstanding how the PID controls things. The "output" terminals on the PID do not have any sort of power supply driving them from within the PID. They are just two sides of a switch. You connect a source to one of the terminals and when the PID says "ON", it will connect that terminal to the other one.

You can run DC or AC through it, but you have to supply the source voltage to one of the terminals.

 

[rod734]

The PID actually runs on anything from 90VAC to 250VAC. It will work fine on 110V.

I was just getting back on to ask you about that, so if I run it on 110 Ill just get 110 out the back?

 

[Walker]

no. you need to think of the PID's output as a totally separate thing than the power supply for the PID. the output is just two screw terminals. call them A and B.

If you connect 12VDC to terminal A, then when the PID says "go" that 12VCD will show up on terminal B.

If you connect 110VAC to terminal A, then 110VAC will show up on terminal B.

The PID can be running on 110VAC or 220VAC or whatever. It's unrelated to the output part of the PID.

 

[rod734]

I might add I found a discrempensy In the wireing diagram that came wiath my unit compaired to the one on the Rex website. The power terminals and the alarm terminals are reversed. I wrote an email to Rex to varifie the proper wireing diagram.

http://www.rkcinst.co.jp/english/pdf_manual/imnzc21e1.pdf

this is a link to the c100 wireing will probobly have to copy and paste

 

[rod734]

I think you might be misunderstanding how the PID controls things. The "output" terminals on the PID do not have any sort of power supply driving them from within the PID. They are just two sides of a switch. You connect a source to one of the terminals and when the PID says "ON", it will connect that terminal to the other one.

You can run DC or AC through it, but you have to supply the source voltage to one of the terminals.

ok I see what your saying, I was thinking of the input power going through the pid and the pid was sending it out the back terminals. These replies are comming faster than I can type.

 

[rod734]

I think you might be misunderstanding how the PID controls things. The "output" terminals on the PID do not have any sort of power supply driving them from within the PID. They are just two sides of a switch. You connect a source to one of the terminals and when the PID says "ON", it will connect that terminal to the other one.

You can run DC or AC through it, but you have to supply the source voltage to one of the terminals.

I wa compleatly missunderstanding it, this sheds a whole new light on things. So if I run 12 volts through the relay how would this differ from an ssr out. The manual said it had ssr capibilities as did the listing on ebay. could this be what they are refering to. And since the wireing diagrams don't jive, this could be why people are having trouble getting to work properly. The one on the ReX website said revised wireing diagram.

 

[Walker]

I wa compleatly missunderstanding it, this sheds a whole new light on things. So if I run 12 volts through the relay how would this differ from an ssr out. The manual said it had ssr capibilities as did the listing on ebay. could this be what they are refering to. And since the wireing diagrams don't jive, this could be why people are having trouble getting to work properly. The one on the ReX website said revised wireing diagram.

No, this is not what they were referring to on the ebay listing. That "voltage pulse output" is something that is available on a different model of the C100, but not available on the one actually being sold.

It differes from an SSR output in two ways:
- you have to provide the DC votage source. a PID with a real SSR output has that stuff built into it
- a real SSR output does not have moving parts like this mechanical relay

You will get something that functions relatively the same as a proper SSR output if you run a DC power source through the built-in relay to drive an SSR, but you will hear the thing clicking as the relay turns on and off. And the amount of clicking on and off will decrease the life of that little relay.

 

[betadave]

The use of a phone charger to avoid opening the case and finding the voltages driving the relay seems good to me. The current needed is very small and the relay is rated for 10 amps. Should last a long time. I also figured out that the cycle time is adjustable with the T setting showing and inverted L. Make the cycle time something like 20 seconds or more and the relay does not actuate too much. Electrical heating is slow and something like 60 seconds might be just fine.

The other thing I had to figure out by trial and error is the setting SC is an adjustment for the thermocouple readout to correct for errors. I could not find any mention of what that was but finally stumbled into correcting the TC readout to match a trusted thermometer.

 

[betadave]

About the wiring diagram, I followed the sticker on the case as I did not have an english instruction set at the time and the controller works. The diagram in the sheet is indeed wrong. It may explain why some of them seem defective?

 

[Walker]

yeah, documentation sucks for the things. some sellers have good instructions. some have terrible ones.

The one my friend bought is definitely defective. temp input is flat out broken.

Regarding running DC thorugh the built in relay. It will probably work very well and last long enough to make the PID worth the low amount of money spent, but it really is super easy to crack the case open and find the place where wires need to be attached to drive an SSR directly.

I'm sure it'll do you fine using the built in relay.

 

[rod734]

I got a reply from the Rex company regarding the wireing difference I found. He sent me an owners manual PDF and informed me of fake Rex pids that were being made in China and sold on ebay. I sent him MY SN as asked so he could verify if it was one of theirs, but I think it's a fake because the terminal pattern wasn't the same.

 

[Walker]

I was wondering if these were fakes. If you actually search for "REX C100", you find only a few hits and they are up in the $75 range.

 

[rod734]

I was wondering if these were fakes. If you actually search for "REX C100", you find only a few hits and they are up in the $75 range.

I know, I researched the company while I was considering buying one of these, and the seem to be a solid company. I never thought about fakes being sold.

 

[rod734]

My C100 is rated a 250 volts 3 amps on the relay. I got a decent instruction manual and the wireing diagram matched the sticker on the unit. I just noticed while browsimg the Rex website the wireing diagram they showed was different, so I contacted them and thats when I found out about the fake units. My aquariam controller I got to build a fermenting chamber is rated at 120 volts 10 amps. The deagram on the sticker on the C100 is probably correct for the unit, but I think it is probably a fake Rex C100. I will know for sure when the Rex company conferms the SN.

 

[weirdboy]

What is wrong with just using the mechanical relay that is on there? It doesn't have to be an SSR to get the job done.

 

[rod734]

What is wrong with just using the mechanical relay that is on there? It doesn't have to be an SSR to get the job done.

Thats what I will do on the build. If the relay fails at some point, then I will look into using the relay switch voltage to switch my SSR.

 

[mattd2]

What is wrong with just using the mechanical relay that is on there? It doesn't have to be an SSR to get the job done.

Thats what I will do on the build. If the relay fails at some point, then I will look into using the relay switch voltage to switch my SSR.

I saw on one of the ebay auctions for the mid priced Stetos (sp?) PIDs that if the mech relay is sued they suggest a duty cycle time of at least 20 seconds. Don't know if you can change this on the REX.

 

[betadave]

The REX C100 I got from eBay does have control over the duty cycle. In the programming process, the term for duty cycle is called T and shows as an inverted L. It is default set for 20 and can be adjusted with the up/down arrows as you would expect. I validated that by setting it to 3 and letting the relay click frequently and then back to 20 where it slowed down.

 

[Walker]

The REX C100 I got from eBay does have control over the duty cycle. In the programming process, the term for duty cycle is called T and shows as an inverted L. It is default set for 20 and can be adjusted with the up/down arrows as you would expect. I validated that by setting it to 3 and letting the relay click frequently and then back to 20 where it slowed down.

I don't think that's what he meant by "duty cycle". On PIDs like the one from Auber, you can adjust that parameter that you are talking about (the output cycle) and then tell the PID to manually drive the output for some percentage of that output cycle. It ignores the temp probe input in that mode.

That sort of duty cycle adjustment allows you to control the strength of a boil by having your element effectively running at a fraction of it's power. The REX-C100 doesn't have that sort of control.

 

[Brewing Clamper]

... The REX-C100 doesn't have that sort of control.

So I'm thinking of doing a single vessel system from my current 4500W e-keggle. I was thinking of using this thing as a temp controller for BIAB mashing then ramping it up to a boil and controlling the boil with it... I won't be able to dial it down if the boil is too strong?

 

[Walker]

So I'm thinking of doing a single vessel system from my current 4500W e-keggle. I was thinking of using this thing as a temp controller for BIAB mashing then ramping it up to a boil and controlling the boil with it... I won't be able to dial it down if the boil is too strong?

correct. this is purely a temperature controller. a boiling kettle has a constant temp, and it doesn't matter if it's a gentle simmer or a violent geyser.\

You will not be able to control the strength of the boil with this controller.

 

[Brewing Clamper]

Hmm... guess it's back to the drawing board. I'm basically thinking of building something like the Braumeister single vessel thing. I currently use a home built PWM to control the boiling kettle but no accurate temp controller...

Hey Walker, can you point me to your controller build thread? I couldn't find it.. Thanks man!

 

[Walker]

Hmm... guess it's back to the drawing board. I'm basically thinking of building something like the Braumeister single vessel thing. I currently use a home built PWM to control the boiling kettle but no accurate temp controller...

Hey Walker, can you point me to your controller build thread? I couldn't find it.. Thanks man!

AH... if you have a PWM already, then you can use the PID for temp control during the mash and then switch over to the PWM for boil control.

that's what I do on my system.

I just have a DPDT switch on the SSR control signals from the PID and the PWM to let me select which device is in control of the SSR.

I don't really have a build thread for my system. There is a thread, but it has very little info in it.

 

[betadave]

I don't think that's what he meant by "duty cycle". On PIDs like the one from Auber, you can adjust that parameter that you are talking about (the output cycle) and then tell the PID to manually drive the output for some percentage of that output cycle. It ignores the temp probe input in that mode.

That sort of duty cycle adjustment allows you to control the strength of a boil by having your element effectively running at a fraction of it's power. The REX-C100 doesn't have that sort of control.

You are right as far as I can tell. To trick the REX into that you would need to adjust the P to some setting and then set the I and D to 0 so the system is proportional only. You can then set the temperature number to something close to the target and the output will be directly proportional to the difference from the PV and the SV. So, if the boiling temperature is 100C, setting it to 102 with a P setting of 20 might give 10% output. Since I don't know if the P sets the error to full output, I am just making that up but it would be easy to find out by trial and error. The P setting would just be wide enough to make control easy. You would have to reprogram to switch back to temperature control. Far too much hassle.

 

[betadave]

I set up a sous vide cooking setup today with my REX C100. I am using the relay driver voltage to run an SSR and using that to run a heating element. It works just fine. I allowed autotune to find the PID settings and after the autotune ran, the temperature is holding at 60. Since I can't see 10ths, I have no idea how close it controls but it cycles on and off without showing anything other than 60 so I assume it is holding within .5C or some rounding would let me see either 59 or 61.

So, basically, the guy on eBay is a skunk but the controller can be used as an SSR controller and get good results if you crack open the case and bring the relay driver voltage out. I don't mind that the relay makes a click as it lets me know it is working. I don't have to look to see the tiny LED.

I am sure that a low budget creative approach will work for controlling the heat rate with the proportional only setting. It would require that you write down the correct P, I, and D numbers so you can reset your unit for temperature control but, in principle, it is fine. It would require some playing but for some P setting, you could control the percentage of on time to match, say, 10 times the degrees over the process temperature that you set your set point. It should be easy to sort out with a stopwatch and five minutes of your tinkering time.

Cool piece of $10 junk. Now I will put it in a case of some sort and allow it to serve as my sous vide cooker for eternity.

 

[ferari12]

I succeeded in using the REX-C100 to operate an SSR also. I removed a relay and ran the switching signal straight to the terminal posts. Here is a PDF with before and after pics: http://www.mediafire.com/?bbqzfm58c7lpsbo

 

[betadave]

Yes, indeed. I built a box from left over floor joists to fit a stainless steel pan that I already owned, insulated it with fiberglass, put in an old 250 watt lab heating pad, installed my modified controller running my SSR in a metal case I had laying around and now I have a very nice sous vide cooker that controls within one degree C. Total cost was around $15. Not bad for a piece of junk. A commercial sous vide cooker of that size would have cost me over $1,000. It is not beer but it makes nice meals to enjoy with my beer. I cooked 4 tri tips at the same time and served 24 people and had left overs with the thing.

Just for the record, I also served american pale ale, brown ale and irish stout at the party. All home brew. Good times.

 

[morzh]

So, basically, the guy on eBay is a skunk but the controller can be used as an SSR controller and get good results if you crack open the case and bring the relay driver voltage out.

Hey guys,

I am new here and just saw that thread - was looking for C100 setup.
But I wanted to tell you this: on ebay those guys sell "M"-type C100 (relay output). However the guy clearly advertised SSR drive output ("V"-type).

Here's what I did - I wrote the guy and he admitted the error in description. I told him I could not use the PID, and first he wanted me to pay him another 15 bucks for the right type. I told him (he sold his for 19 bucks, and the SSR -type sells for 24 bucks) that I will pay him extra 5 bucks.
He agreed and thanked me profusely.
All in all, he was very polite, and only tried to haggle in the beginning.
So I got my SSR drive C100. And, he did not want the other one back, so I have it. Though I have no use for it.

What I mean - ask the buyers if they sell "V"-type (SSR driver) and should they screw you on description - they will pick up the tab. Their fault.
-----


Anyway, I had a question: when using K-type thermocouple (mine is 0-400C) supplied with the PID, initially, until I start heating it up, it shows some negative temperature. Is it the error in the beginning of the range? Anyone noticed that?

 

[morzh]

I succeeded in using the REX-C100 to operate an SSR also. I removed a relay and ran the switching signal straight to the terminal posts. Here is a PDF with before and after pics: http://www.mediafire.com/?bbqzfm58c7lpsbo

Actually I just realize the one I got for the SSR is defective - this is why it measures -55C when it is 25C.
The other one, with the relay output, measures all correctly - boiling water is 100C.

So how did you say you popped up the case? Can't see any tabs. I don't think this Chinese guy will send me another one and I hope to use that relay type as long as I can open it up.