AIO module RTD precision for temperature

[xipherx]

Hi all,

I'd like to have a clarification about what it's indicated in your AIO Datasheet, more precisely under Technical Data for the "Input Resolution in process Image" field you show the following:
Voltage: 1mV (16bit)
Current: 1microA (16bit)
Temperature: 0.1K (16bit)

What do you exactly mean with "K"?
Can I consider as valid what you say in the RTD Tutorial: "Basic Knowledge RTD Measurement (Con)", at the beginning of the page: "....The process image (PA) then contains the temperature values of the two measuring inputs in the unit 1/10 °C" ?

So can I use RTD channel for measuring a temperature with PT100 sensor with a 0.1 °C precision?

Many thanks in advance!

Kind Regards

[pi_admin]

Hi Xipherx,

"K" is the symbol for the temperature unit "Kelvin".

Regarding your second question: Yes, 0,1 °C is equal to 0,1 K and yes, you can measure/display the temperature in 0,1 °C steps.

If you want to know more about Kelvin and the conjunction between Celcius and Kelvin, you might wanna take a look at the Wikipedia page:
https://en.wikipedia.org/wiki/Kelvin

[xipherx]

Many thanks,

I'm trying to use your AIO module in an industrial automation and monitoring project proposal with a client of mine.
My previous question was because I'd like to offer to my client a different technology from Siemens S7.
More precisely I'm trying to understand if your AIO module is comparable to the 6ES7531-7KF00-0AB for temperature measurement characteristics : https://support.industry.siemens.com/te ... aller=SIOS

For example:
For the Siemens AIO module we have:
Linearity error (relative to input range), (+/-): 0.02%
Temperature error (relative to input range), (+/-): 0.005 %/K; With TC type T 0.02 ± % / K
Repeat accuracy in steady state at 25 °C (relative to input range), (+/-): +-6°C

Operational error limit in overall temperature range
Voltage, relative to input range, (+/-): 0.3%
Current, relative to input range, (+/-): 0.3%
Resistance, relative to input range, (+/-): 0.3%
Resistance thermometer, relative to input range, (+/-): Ptxxx standard: ±1.5 K, Ptxxx climate: ±0.5 K, Nixxx standard: ±0.5 K, Nixxx climate: ±0.3 K Thermocouple, relative to input range, (+/-) Type B: > 600 °C ±4.6 K, type E: > -200 °C ±1.5 K, type J: > -210°C ±1.9 K, type K: > -200 °C ±2.4 K, type N: > -200 °C ±2.9 K,type R: > 0 °C ±4.7 K, type S: > 0 °C ±4.6 K, type T: > -200 °C ±2.4 K

Basic error limit (operational limit at 25°C)
Voltage, relative to input range, (+/-): 0.1 %
Current, relative to input range, (+/-): 0.1 %
Resistance, relative to input range, (+/-): 0.1 %
Resistance thermometer, relative to input range, (+/-): Ptxxx standard: ±0.7 K, Ptxxx climate: ±0.2 K, Nixxx standard: ±0.3 K, Nixxx climate: ±0.15 KThermocouple, relative to input range, (+/-) Type B: > 600 °C ±1.7 K, type E: > -200 °C ±0.7 K, type J: > -210 °C ±0.8 K, type K: > -200 °C ±1.2 K, type N: > -200 °C ±1.2 K, type R: > 0 °C ±1.9 K, type S: > 0 °C ±1.9 K, type T: > -200 °C ±0.8 K

Can you tell me if your AIO module is in the same order of magnitude of the Siemens?

Many thanks in advance.

Best Regards

[dirk]

Hi Xipherx, please have a look at the datasheet of the AIO Module. If you still have questions please do not wait to ask them.

[FMW]

I'm having the same question/concern, prior buy.
I guess and hope there is a bit of confusion between resolution and accuracy.

I need to setup a project with 16 RTD, and I have to control some temperatures with set points at 0.01°C cerca. For me, even if the accuracy is around 0.5°C, it does not matter as my process will auto-adjust the temperature set points based on other measures, but it is still important that I can read and process temperatures with a precision of 0.01°C.

So my question remains, because on the RevPi 'store' it is mentioned "The 2 RTD inputs enable temperatures to be measured with high precision from -165°C to +600°C in steps of 0.5°C".
If so, these RevPi AIO won't be suitable to my application.

Any thoughts from KUNBUS engineers ?

[dirk]

Hi FMW, I have successfully measured with a RevPi AIO Module and a 4-wire PT1000 temperature in steps of 0.1°C.

Code: Select all

pi@RevPi99988:~ $ piTest -r RTDValue_1
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 222 dez (=00de hex)
2 Byte-Value of RTDValue_1: 224 dez (=00e0 hex)
2 Byte-Value of RTDValue_1: 227 dez (=00e3 hex)
2 Byte-Value of RTDValue_1: 231 dez (=00e7 hex)
2 Byte-Value of RTDValue_1: 233 dez (=00e9 hex)
2 Byte-Value of RTDValue_1: 235 dez (=00eb hex)
2 Byte-Value of RTDValue_1: 235 dez (=00eb hex)
2 Byte-Value of RTDValue_1: 236 dez (=00ec hex)
2 Byte-Value of RTDValue_1: 236 dez (=00ec hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)
2 Byte-Value of RTDValue_1: 237 dez (=00ed hex)

Take a look at this documentation:

• How to Configure RTD Channels for Temperature Measurements
• Basic Knowledge RTD Measurement (Con)

Test Setup