NI VISA - Temperature sensor - serial communication - 25*35 pixels - slow print to labview

[Aaatif]

Hello, 

I am using a temperature sensor which has 25 * 35 pixels and i have programmed it to print the temperature 8 or 16 frames per second. On any serial application it seems to work as expected but when i try to have labview display it it seems to print very slowly.

I have tried to go into device manager and change the baud rate to match my program but it did not help.

I have previously programmed a similar sensor which had 4*16 pixels (temp values) and it worked absolutely fine and i at least did not have this problem.

Attached below is the previous .vi file for the 4*16 pixels sensor which works great and also the .vi for the 23*35 pixels sensor which has the problem of printing the data very slowly ( with a delay).

A screen capture is also included.

Please Advise.

Thank you 

Atif

[Blokk]

Temperature sensor / pixels? I have no idea what kind of sensor you have. Could you state the manufacturer, and the model? Do you have a manual? Does the manual explains what kind of communication protocol you need to use? In your VI you have only a simple VISA Read in a While loop. Often, a communication consists of a request/response pairs (VISA Write / Read) using a properly set termination character. I repeat, you need to show us the manual, otherwise we can only guess what you do wrong...

[Aaatif]

Hi Blokk,

It is a Melexis sensor MLX90621 a higher version of it. It uses the i2c protocol.

I have attached the .vi in the question which is working, that i was able to create for the 4*16  pixels (when i mean pixels - it is a temperature map with 4*16 = 64 temperature values  which are being printed on the screen - think of it as a small IR camera )  

The problem is when i use a similar higher resolution sensor with a greater temperature map/pixels  24*35 instead of 4*16  the data visualized in labview through the visa read is very slow and not as quick.( please see the zip file attached in the question,  it consist of a video of what is happening) 

Attached below is the video file for the 4*16 sensor - you can see how quickly the data is printed in labview vs the other video file for the 24*32 bit sensor.( please play both the video files and you will know what i am trying to say)

The data is received through the serial port - it is 8 frames per second. for the new and the old sensor.

I have attached the data sheet for the lower resolution sensor but currently cannot post the data sheet for the higher resolution sensor. the are basically same just higher in resolution/ data acquired/ pixels.

Also i have alredy a microcontroller programed for this sensor - i dont need a visa write. 

please advise 

Atif

[Blokk]

"Also i have alredy a microcontroller programed for this sensor - i dont need a visa write. "

So you have a microcontroller, which interfaces the I2C sensor to RS232? I think what you should check, how is this microcontroller is configured, and match the settings in your LabVIEW code... I am not really familiar with such configuration, someone else here might give better ideas what to check/change in your setup...

[Yamaeda]

It seems your sensor sends the data as text, so i'll assume 8 bytes/values.

25*35*8=7000bytes

115200 bit/sec ~12000 bytes/sec

You'll get 1,5 values/sec, does that seem about right?

In order to get 8/sec, you'll need roughly 25*35*8*8*10 bits/sec = 560kbit/sec

/Y

[Aaatif]

Hi Yamaeda, 

Yes that sound about right. - is there something i am doing wrong ? or could you guide me through this ?

Atif