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Post by user222 on Jun 6, 2024 10:03:34 GMT -5
Hello, I am using Lakeshore model 372 with 2 Cernox Lakeshore diodes ( CX-1050-CU-HT-1.4L). I uploaded the calibration curves specific to each diode in the Lakeshore. One diode in wire as a control (input A) and the other as measurement input.The temperature controller measures a resistance (around 81 ohms) which is correct for room temperature (around 293 K). However it doesn't compute any corresponding temperature value (Here is a picture of the display screen :  ). Is there any way to solve this problem? Have a nice day! |
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Post by Lake Shore Jeff M on Jun 6, 2024 10:37:53 GMT -5
I have a few questions that I need answered:
1.0 When you configured the inputs, did you select the curve you entered
2.0 When you loaded the curves using the curve handler application did the computer
you used use a comma or decimal point for numeric entries?
3.0 Confirm that the curve you loaded were provided by Lake Shore.
I suspect that either you did not assign the respective curve to the input or the curves you loaded are corrupt due to the computer using a comma and not a decimal point which version 9 of our curve handler application requires.
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Post by user222 on Jun 7, 2024 3:25:24 GMT -5
Thank you for your quick answer! To answer your questions : - We did select the curve we entered when configuring the input as proven by the following picture:
 ![]() - The computer uses decimal point
- We used the specific curves provided by Lakeshore
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Post by Lake Shore Jeff M on Jun 7, 2024 6:30:33 GMT -5
How did you enter the curve as what is seen in the picture is not the correct data for sensor X202050. The curve for NTCRTD sensors like the Cernox Sensor must be in the Base 10 Log Ohm of the resistance versus Temperature in Kelvin. What I see if Ohms versus Kelvin.
Here is what the curve header and first few curve points should look like:
Sensor Model: CX-1050-CU-HT-1.4L
Serial Number: X202050
Data Format: 4 (Log Ω/Kelvin)
SetPoint Limit: 325 (Kelvin)
Temperature coefficient: 1 (Negative)
Number of Breakpoints: 168
No. Units Temperature (K)
1 1.87472 325.000
2 1.88006 320.500
3 1.88669 315.000
4 1.89285 310.000
5 1.89912 305.000
6 1.90678 299.000
7 1.91330 294.000
8 1.92064 288.500
9 1.92745 283.500
10 1.93509 278.000
For the complete list of points, you can open the file X202050.340 in Notepad or any text editor.
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Post by user222 on Jun 7, 2024 7:22:51 GMT -5
We managed to solve the issue by uploading the old format 340 file.  Thank you for your help and quick answer! Have a nice day. |
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Post by Lake Shore Jeff M on Jun 7, 2024 7:35:32 GMT -5
The Model 372 offers two different temperature interpolation methods that require different curve files. For the standard straight line interpolation it used the file with the .340 extension. For the Cubic Spline interpolation method, you would need to load the file with the .curve extension.
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