Pico Log Calibration Data for Thermocouples?!

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allankey
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Joined: Tue Apr 29, 2014 9:12 am

Pico Log Calibration Data for Thermocouples?!

Post by allankey »

Hi, I am using the TC08 USB data logger. Please can you tell me where I can find the in-built calibration data that is used to determine the temperature? I am using a T-Type.

Thanks

Hitesh

Re: Pico Log Calibration Data for Thermocouples?!

Post by Hitesh »

Hi allankey,

Are you looking for information in order to self-calibrate the device or apply some sort of scaling?

Have you referred to the following webpage?

http://www.picotech.com/applications/thermocouple.html

If you are looking to convert temperature readings in microvolts into temperature, the user manual for the RS-232 TC-08 states the following:
To convert a thermocouple reading, in microvolts, into temperature, you will need to
use a table containing microvolt readings at various temperatures for the type of
thermocouple that you wish to use. You can obtain these tables from the British
Standards Institute or thermocouple manufacturers.

First, take the cold junction temperature and use this table to convert it to microvolts.
Add this onto the microvolt reading from the thermocouple. Convert the total back to
temperature using this table.
Regards,

jerzydziewierz
Newbie
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Joined: Thu May 08, 2014 7:27 pm

Re: Pico Log Calibration Data for Thermocouples?!

Post by jerzydziewierz »

So, just to make it completely clear,

Does USB TC-08 do the cold junction compensation when the mode is set to return the result in degrees centigrade, (when eg. using through the usbtc08.dll and user application),

or does the application has to do the calibration - by *unconverting* the temperature back to microvolts, substracting the cold junction voltage, and then converting back to degrees centigrade?

Regards,

Hitesh

Re: Pico Log Calibration Data for Thermocouples?!

Post by Hitesh »

Hi,

The previous post referred to the situation where scaling can be applied to the readings if required when using the PicoLog Recorder software.

When calling the API functions, the readings will be returned in degrees Celsius unless X is specified in which case it will be voltages.

If you are returning the values in degrees there is no need to convert the readings. You will need to enable the cold junction channel.

I hope this helps.

jerzydziewierz
Newbie
Posts: 0
Joined: Thu May 08, 2014 7:27 pm

Re: Pico Log Calibration Data for Thermocouples?!

Post by jerzydziewierz »

Hitesh wrote:Hi,
If you are returning the values in degrees there is no need to convert the readings.
I hope this helps.
From this, should I understand, that as long as the cold junction channel is enabled, the temperature channels in the degrees centigrade mode are already being compensated?

Hitesh

Re: Pico Log Calibration Data for Thermocouples?!

Post by Hitesh »

Hi,

The cold junction compensation will be applied regardless of whether the channel is 'enabled' in the API call. Cold junction compensation will not be applied if you are only measuring milliVolts.

Calling this function will allow you to view the cold junction temperatures if you wish to.

Hope this clarifies things.

jerzydziewierz
Newbie
Posts: 0
Joined: Thu May 08, 2014 7:27 pm

Re: Pico Log Calibration Data for Thermocouples?!

Post by jerzydziewierz »

It is now clear, thank you.

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