PID reading wrong temperature

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wuttheheeck

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I am on the final stages of my herms system, the only thing holding me back is these dam temperature sensors.

I am using a mypin Ta4 style PID controller with a 2 wire PT-100.

Using this diagram I have jumped the terminals from 7-10 and 8-9
3677d1362363867-pid-wiring-trouble-please-help-mail.google.com.jpg


My PID is registering a temp more than 100* off form actual temperature.

Is there any way to calibrate a PID and tell it what 32* or boiling is?

Running out of ideas here,
Thanks
 
I can only tell you that there is another thread here somewhere breaking down the exact wiring configuration for a two wire pt-100....once its right you'll find there's no calibrating necessary....
I can across the other thread while searching "my pin and pt-100" together.
 
Should I use PT mode in my pid or use a RTD mode. From what i read on other forms, most PT-100 use 3 wires to account for line resistance.
 
Update

i am within +/- 5 degrees when i am using the K setting for input and only using terminals 7 and 8

about to run a boil test, more updates to follow
 
you're right. No luck with it on K setting. I've tried jumping the additional terminals like many forums suggest and that doesn't give me any help.
 
If your sensor was wired to pins 7 and 8 then your wiring was indeed correct.

Can I ask where you got your sensor? 2 wire RTD probes (pt100 is a type of RTD) are not all that common, typically 3 wire for hobbyist level gear, and if you bought it from a chinese source on ebay there's a chance it might actually be a type K thermocouple!

When you say no luck with the K setting you had a value from it though? These can be very out at boil, I recently did a calibration on my PID setup in work and it was 8C (14F) out at boiling temperatures...
 
big_len said:
If your sensor was wired to pins 7 and 8 then your wiring was indeed correct.

Can I ask where you got your sensor? 2 wire RTD probes (pt100 is a type of RTD) are not all that common, typically 3 wire for hobbyist level gear, and if you bought it from a chinese source on ebay there's a chance it might actually be a type K thermocouple!

When you say no luck with the K setting you had a value from it though? These can be very out at boil, I recently did a calibration on my PID setup in work and it was 8C (14F) out at boiling temperatures...
Click to expand...

I was getting a positive reading while only on the 7-8 pin and set as a K. I did buy it exactly how you said, it was cheap (lesson learned). I am considering to just invest on something off auber or an RTD off amazon.

I was reading ~145* at garage temperature
 
big_len said:
If your sensor was wired to pins 7 and 8 then your wiring was indeed correct.

Can I ask where you got your sensor? 2 wire RTD probes (pt100 is a type of RTD) are not all that common, typically 3 wire for hobbyist level gear, and if you bought it from a chinese source on ebay there's a chance it might actually be a type K thermocouple!

When you say no luck with the K setting you had a value from it though? These can be very out at boil, I recently did a calibration on my PID setup in work and it was 8C (14F) out at boiling temperatures...
Click to expand...

I was getting a positive reading while only on the 7-8 pin and set as a K. I did buy it exactly how you said, it was cheap (lesson learned). I am considering to just invest on something off auber or an RTD off amazon.

I was reading ~145* at garage temperature
 
big_len said:
Was this in K mode with no jumpers or PT100 mode with jumpers ?
Click to expand...

It is in K mode with no jumpers. Getting a closer reading, but still about 15 off. This is consistent with all three therms im using (labled pt-100) but apparently a thermocouple.

Any way to adjust for this difference?

:mug:
 
wuttheheeck said:
I was getting a positive reading while only on the 7-8 pin and set as a K. I did buy it exactly how you said, it was cheap (lesson learned). I am considering to just invest on something off auber or an RTD off amazon.

I was reading ~145* at garage temperature
Click to expand...

My pt-100 sensors were $6 and my my pin pies were 21 and 26 bucks and they are both dead on with my infrared temp gun and my two analog thermometers (well within one degree) mine are three wire.
 
augiedoggy said:
My pt-100 sensors were $6 and my my pin pies were 21 and 26 bucks and they are both dead on with my infrared temp gun and my two analog thermometers (well within one degree) mine are three wire.
Click to expand...

I would agree with this, I have also done alright with 3-wire low cost probes. I would probably buy one anyway, off ebay, as it only be about $5 as augiedoggy said.

As for this probe, have you tried it in boiling water? It might be a conicidence that its reading close to ambient-ish temperatures in K mode and it is a pt100.
 
big_len said:
I would agree with this, I have also done alright with 3-wire low cost probes. I would probably buy one anyway, off ebay, as it only be about $5 as augiedoggy said.

As for this probe, have you tried it in boiling water? It might be a conicidence that its reading close to ambient-ish temperatures in K mode and it is a pt100.
Click to expand...

Thank you both for your help, I plan on running a few more tears with the them as they are. If the reading stays x degrees warmer consistently I will adjust my calculations temporarily but then also purchase some better sensors, or at least a 3 wire Pt100

@augiedoggy where did you find them for $6? I could only find bare k type for that cheap, and I've read there are issues extending the leads with xlr cables like my my setup
 
wuttheheeck said:
Thank you both for your help, I plan on running a few more tears with the them as they are. If the reading stays x degrees warmer consistently I will adjust my calculations temporarily but then also purchase some better sensors, or at least a 3 wire Pt100

@augiedoggy where did you find them for $6? I could only find bare k type for that cheap, and I've read there are issues extending the leads with xlr cables like my my setup
Click to expand...

On eBay... I bought two shipped from supplier in china... they took a couple weeks though... I too have the xlr connectors setup with mine with no issues...
Here's where I bought mine.

http://www.ebay.com/itm/111179002321?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
 
wuttheheeck said:
It is in K mode with no jumpers. Getting a closer reading, but still about 15 off. This is consistent with all three therms im using (labled pt-100) but apparently a thermocouple.

Any way to adjust for this difference?

:mug:
Click to expand...

If you have a multimeter just measure your probe resistance. If it's PT-100 RTD its resistance should be around 100-120 Omh
 

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