Rex c100 PID owners - a must know! (how to turn off digital frequency)

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KnightDesign

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Hi everyone,

I just found out something very important with my own rex c100, and figured others might not know either.

So, it turns out the engineers who made the damn thing included a default feature that tells you an incorrect PV value just to keep you happy. I think it can be out by a good couple of degrees Celsius which is really not ideal for fermentation or mashing.

I found this out when I changed the SV value by a few degrees and the PV value automatically jumped to the new value. This meant I was fermenting at a couple of degrees celsius ABOVE what I wanted, not cool.

But thankfully you can change this! It's called the DF (digital frequency?) and can only be accessed through the second COD menu thing.

If you have a rex c100 (mine is a 'Berme' brand) then keep this manual in your favourites - http://style.oversubstance.net/wp-content/uploads/2015/01/ManualREX-C100.pdf

So here is the process to do so (with mine anyway, I know there are lots of different types and whatnot).

Here is your PID, hold the SET button for about 4 seconds to bring up the settings.




Then keep pressing SET to get to the 'LCY' stage, and for me I turn it to '1000' to unlock the special menu thing. Yours may be different, check your manual.




Then you need to hold the SET button to get back to the normal home screen.



Now, you hold SET and '<' buttons for around 4 seconds to bring up the COD menu.



This is where you want to use the up/down buttons to change the last 0 to a 1.



Then press SET again to move into the menu.



You want to keep pressing SET until you come across 'DF' it should be set to 0001.



Change the last 1 to a 0.



You have successfully turned off the stupid feature! Now to get back to the home screen. I think I just didn't press anything for about 30sec's and it auto went back to the home screen. If not, try holding SET.

Remember to turn your 'LCY' thing back to whatever you want to keep it as. I keep mine as 0000 which keeps everything saved and unlocked so I can change it easily.




Now your PV value should actually be what the PID is reading.

Hope this helps some people out there!

Cheers,
Brendan
 

JohnnyGunn

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Hey KnightDesign,

Thanks for the info!

I'm just curious to know if you had to do the SSR modification to your particular REX-C100? I got the Berme branded PID from someone and I haven't really looked into it to see if it natively supports SSR.

One other thing, do you know if we can use an RTD probe with it, or can we only use the K type thermocouple?

Thanks.
 

augiedoggy

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Hey KnightDesign,

Thanks for the info!

I'm just curious to know if you had to do the SSR modification to your particular REX-C100? I got the Berme branded PID from someone and I haven't really looked into it to see if it natively supports SSR.

One other thing, do you know if we can use an RTD probe with it, or can we only use the K type thermocouple?

Thanks.
You can use rtd probes with them... I have one I used with it and an ssr but ditched it for the vastly superior $30 mpin td4-snr with fuzzy logic Fahrenheit and manual pwm mode built in..

This thread is just another reason im glad I did so :) rather than discover this after 3 years of use..
 
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KnightDesign

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Hey KnightDesign,

Thanks for the info!

I'm just curious to know if you had to do the SSR modification to your particular REX-C100? I got the Berme branded PID from someone and I haven't really looked into it to see if it natively supports SSR.

One other thing, do you know if we can use an RTD probe with it, or can we only use the K type thermocouple?

Thanks.

Hi and no worries!
Some types support SSR's and some don't. I also don't know what amperage those with SSR's are build for either.
I hacked mine to output directly to a 40A SSR which does me fine. You can use the internal contact relay for running heat pads and whatnot though, just not a 2500W element...

I think you can change a setting in a menu somewhere which changes the type of temperature sensor you can plug in. See the online manual I linked and it might help with that.
 
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KnightDesign

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You can use rtd probes with them... I have one I used with it and an ssr but ditched it for the vastly superior $30 mpin td4-snr with fuzzy logic Fahrenheit and manual pwm mode built in..

This thread is just another reason im glad I did so :) rather than discover this after 3 years of use..
I think you are correct aha. They are a bit of a pain to use but it's what I've got. I'm going to the STC 1000 next as they support both heating and cooling and have a simpler interface. And are only $30 nz. This doesn't have any kind of logic as far as I'm aware though, so I'll keep using my Rex for mashing and such things.
 
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...So, it turns out the engineers who made the damn thing included a default feature that tells you an incorrect PV value just to keep you happy...
Doesn't sound right - engineers don't really care how you feel!

Anyway, have you looked at another manual to find out what this setting actually does? Maybe you are improving one aspect but making something else wrong, or maybe its a calibration thing, etc?

-BD
 
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KnightDesign

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Doesn't sound right - engineers don't really care how you feel!

Anyway, have you looked at another manual to find out what this setting actually does? Maybe you are improving one aspect but making something else wrong, or maybe its a calibration thing, etc?

-BD
I looked into it and it turns out it's 'digital filtering', which effectively filters (smooths) any minute variations into a nominal sort of process value. Not ideal if you want to keep tight tracks on the temp.
I think it's default just to keep users happy rather than have their PV jump all over and not sit at a constant. I'm not using a good enough thermocouple to have this problem, but it's nice to know I'm getting a raw number, not some sort of average.
 

arjunadval

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Hi I accidentally change setting of my pid rex c100 cod -001 to 0000 now its not changing back to -001 please can you help me in this
 

Lionheart

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Hi Interesting problem. I have bought some of these for different use. I will use it in a beer boiler, but are having problems that pv increases above sv. Any idea how to rectify this?
 
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KnightDesign

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Hi Interesting problem. I have bought some of these for different use. I will use it in a beer boiler, but are having problems that pv increases above sv. Any idea how to rectify this?
Well it really depends cause lots of factors could change this. It could be that the PID values are incorrect for the application you are using it for. Have you tried the auto learning function which adjusts these values for your specific heating method? This helps it understand how long the power source needs to be on to raise the temperature a given amount. There will always be a small amount of overshoot but it should only be a few degrees.

Also I'm not aware of how you would use it for a boiler as the temp would sit at 100 degrees?

Sorry if this is quite rambley.
 

mangkook

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I own BERM Rex-c100 model obviously a clone model. I try searching for DF and on mine it's shows default value of 050 with lowest can be set to 001. Any suggestion?
 

ruanwagenaar27

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I have a REX S100 PID controller connected to a 4000 watt element on my reflux still anybody maybe knows what the settings should be on the controller? The options on the controller is ARU, P, 1,d, AR and LCY?
 

joshua.bastion

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I own BERM Rex-c100 model obviously a clone model. I try searching for DF and on mine it's shows default value of 050 with lowest can be set to 001. Any suggestion?
mines the same. try 100. works way better now, no longer over heats my plates like it always used to... Would heat fast and hard then spike too far and drop back... Now its steady and no longer wasting power unnecessarily...

Mine has a strange option in the settings with the code 'oHn'??? Anyone else? it can be set to 1 or 0. Factory is zero... Different to the oH in basic settings.
 

aringaz

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Thank you man! You have just saved a 2 acres of vinyard from the spring frost! Greetings from Lithuania!!!
Aringas
 
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