LabVIEW ECG AD8232 with Arduino

[Amwajsun]

Hi everyone, I’m a first year student trying to display an ECG signal in LabVIEW using an Arduino Uno and AD8232 sensor.
The Arduino Serial Monitor shows correct changing values (300-800 range) so the hardware works fine, but Waveform Chart shows flat line even though Arduino Serial Monitor shows changing values
My block diagram:
VISA Configure (9600) → VISA Read (30 bytes) → Decimal String To Number → Waveform Chart
The Waveform Chart only shows a flat horizontal line. Read buffer appears empty when running.
Things I already tried:
Decimal String To Number
Scan From String with %d
Spreadsheet String To Array + Index Array
Checked COM port (tried all available)
Closed Arduino Serial Monitor before running
Rebuilt diagram from scratch multiple times
What am I missing? Is there something specific about reading serial data from Arduino in LabVIEW that I’m doing wrong?

 

 

[altenbach · Accepted solution]

It is impossible to troubleshoot your problem from a few blurry truncated iamges.

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@Amwajsun wrote:

Things I already tried:
Decimal String To Number
Scan From String with %d
Spreadsheet String To Array + Index Array
Checked COM port (tried all available)
Closed Arduino Serial Monitor before running

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Just randomly throwing code at it until something sticks seems like the wrong approach.

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@Amwajsun wrote:

Rebuilt diagram from scratch multiple times 

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Do a google search for "Vaas definition of insanity".

SO: Change the string indicator to /-codes, attach your VI after filling all controls with typical default values, and describe how everything is connected.

[Amwajsun]

Thank you for your reply. Please find the VI attached.

To clarify the situation: the read buffer is completely empty when running. Also, the VISA resource name dropdown only shows ‘Refresh’  no COM ports appear at all even with the Arduino plugged in via USB.

The Arduino Serial Monitor confirms the hardware works correctly  values are streaming normally at 9600 baud.

How can i make the COM port appear in LabVIEW?

https://drive.google.com/file/d/1e4ftd2tzWF9hybI1TjW_v4G83bjhNSmn/view?usp=drivesdk

[altenbach]

Very few people have LabVIEW 2026, so please do a "save for previous" (2020 or beloa) and attach it here. (No need to share links of confusing VIs saved without extension.)