Hello, I have a question concerning to the oscilloscope Pc-Lab 2000Lt (PCSGU250). The data after export are really different to the data on the screen.
And the values in the screen are the same when the measurement is done by a multimeter. The oscilloscope was tested with a funtion generator and again, no correlation was found between export values and the values of the screen.
I hope you can give me a hint how to solve this problem.
Thank you very much,
Best regards.
Are you using the File menu options “Export Waveform 1” or are you using the PCSGU250.DLL to export the data to other application?
- Or are you maybe using the File menu option “Save DSO Data” to export the data?
Could you please give more details and an example: Exported data vs. the screen data.
Hello, I’m using save Dso data (.txt) . If you give me an e mail address, it will be a pleasure to send you a detailed report (I cant upload the document in the forum).
Thank you very much
Thank you for the e-mail.
Now I see the problem.
The saved data is not referenced to the ground level of the trace.
The data is the screen image converted to values 0…255. If the trace is in the middle of the screen the value is 127. If the trace is at the top of the screen the value is 255.
In the screenshot image you sent the reference level seems to be about in the middle of the screen. The actual voltage is the difference between the reference level and the actual value.
You may do following:
- Select the Coupling GND for both of the channels CH1 and CH2.
- Adjust the Y-position until the traces of CH1 and CH2 are exactly aligned on the screen.
- Select coupling DC for CH1 only.
Now the CH1 trace position on the screen corresponds to the voltage input. - Save the data.
In spreadsheet calculate dY = CH1 - CH2
Now using this dY you can calculate the real voltage value.
Assuming you had both of the traces aligned before connecting the voltage:
[code]TIME STEP:
100 = 5s
VOLTAGE STEP:
CH1: 32 = 0.3V
CH2: 32 = 10V
N CH1 CH2
1 171 122
2 175 121
3 170 121
4 174 122
5 174 122
…[/code]
Let’s take the data pair # 2
2 175 121
dY = 175 - 121 = 54
And to convert this to voltage:
V = 0.3V * dY / 32 = 0.3 * 54 /32 = 0.506 V
This is quite near the value you got from the DVM and from the oscilloscope screen…
Using the DSOLink.DLL to transfer the data from the oscilloscope to Excel workbook you get automatically the GND reference levels for both channels.
Here an example screenshot:
The voltage values are calculated to columns D and E using the raw data (from the oscilloscope) in columns B and C.
The formula in cell D5 is [color=#000080]=(B5-B$4)*B$3/255/1000[/color]
The formula in cell E5 is [color=#000080]=(C5-C$4)*C$3/255/1000[/color]
Here the oscilloscope screenshot:
Here is the link to download the Excel worksheet containing the macro to read the data from the oscilloscope: box.net/shared/aim4bt5uce
The DSOLink.DLL should be in the Windows\System32 folder.
(Installing the PcLab2000 installs the DSOLink.DLL too.)
Please see the PCSGU250 Help for more details how to use the DSOLink.DLL:
e.g. “Data acquisition to Microsoft Excel”