VOC sensor unreliable serial read (VOC TRAQ)

[Simon-lee]

Hi Folks,

I'm attempting to use Labview (2019) to communicate with a BASELINE® VOC-TRAQ® total volatile organic compound detector.

It came with a bundled application which seems to work quiet well but Its 'one trick pony' and I need additional channels for temperatures and flow rates. 

After reading the manufactures spec sheet, reading the output looked achievable, (the control aspect looks far more complex) 

Using the simple serial example shipped with Labview, I modified it to suit the spec sheet requirement.

The example does work, but not every time its launched. (about 1 in 3)   the other times it either 'times out' or an 'overrun error'.

Can anyone offer suggestions to make more robust . 

Also the shipped example is bytes at port but the forums suggest termination character is an improved method - can anyone offer an insight or example. 

Thanks 

Si

[GerdW · Accepted solution]

Hi Simon,

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@Simon-lee wrote:

After reading the manufactures spec sheet, reading the output looked achievable, (the control aspect looks far more complex) 

Using the simple serial example shipped with Labview, I modified it to suit the spec sheet requirement.

The example does work, but not every time its launched. (about 1 in 3)   the other times it either 'times out' or an 'overrun error'.

Can anyone offer suggestions to make more robust . 

---

The documents only explain how to send commands to your sensor, but I didn't found the description of how to receive data. Maybe you can explain where I can find that information?

When the sensor always sends messages with a TermChar (LF), then your VI should be simplified to:

(Still needs more error checking/handling!)

Getting a timeout error means "no data received", getting an overrun error means "too much data received": both errors for the same sensor communication seem "funny" to me…

[Simon-lee]

Hi GerdW,

Thanks for the reply, I didn't get much time to explore the problem but I did discover the unreliable connection persists.

Now I know the code is correct (Thanks to your code)  I will explore the non-labview possible issues.

1, I'm using a docking station, so I will go directly into the laptop

2, Better quality (shorter) USB cable. 

3,  Alternative OS - I'm using Win 10 but I should be lay my hands on a Win 7 machine to try.

I will report back 

Thanks

Si

[Simon-lee]

Hi GerdW,

I have some follow-up on this question.

1, Alternative USB cable made no difference.

2, If slightly better through a docking station – I assume it act as a powered hub with better power characters (compared to a laptop port)

3, Windows 7 was considerably more stable – I assume this is driver related (there must be a USB to serial converter within the unit). Or my corporate Windows 10 machine has some feature or background software that isn’t 100% compatible.

I guess I will be using the windows 7 machine  on this project – thanks for your assist

Si