Handling data from an A/D converter (serial device)

[crickert]

Hello,

after a lot of searching and reading - I finally have to ask a beginner's question.  😉

How can I handle the collected data converted from (String) HEX to decimals in the

example "Advanced Serial Write and Read.vi" to be displayed in a plot or stored in

a table?

Here's the setup:

I have a very fast 10MS/s A/D converter, which is controlled by a virtual COM port.

For initializing and triggering, the commands are send as Strings followed by a <CR>.

The data is immediately stored on an onboard FIFO memory with a 4096 sample

size. Data is transmitted as HEX strings with a maximum of FFF (which equals 1 V)

and a minimum of 000 (which equals 0 V).

Communication with the converter works fine. The data is picked up from the FIFO

with a while loop (running 4096 times) and the single data values seem to be okay.

But now I have the problem of "combining" them to a dataset that can be displayed

or stored for later handling...

Please give me a hint!

Sincerely

Christian

Message Edited by fumic on 07-09-2009 09:17 AM

[MikeS81]

Hi Christian,

you can build an array and store it in a shift register, which you can create on your while loop. You can also write your data into a chart.

You can read the written data from the chart with a property "history" node (max size is history length).

Mike

Message Edited by MikeS81 on 07-09-2009 11:26 PM

[crickert]

Hi Mike,

thanks for your answer. - I tried to set up a shift register and an array ...

My idea was to first create an empty array (filled with Zeroes) in the first write loop,

because it only runs once.

Then I want to replace the array's indices with the sample values when they are read

by the second loop, which runs for every sample.

In the third step, I want to display the data in a diagram.

The draft I made is ... not quite working as expected!

Could you please help me with that?

Christian

[MikeS81 · Accepted solution]

Hi Christian,

you don't need the for loop. Create the shift register on your while loop. See the attached image.

Mike

[crickert]

Hi Mike,

now it's working!

But only when I initialized the array outside of the while loop,

my data table / plot will be filled with data.

The opposite is true when i do the initialization within the

true case... although I would completely agree to that solution

too.

I am very happy about your great help!!

(Happy)

Christian

[MikeS81]

Hi Christian,

can you show your example where you only initialize the array inside the loop. It should also work. You have to directly wire the array in the false case.

Mike

[crickert]

Attached is an example of the initialization in the "false" case:

all values but the last one are zero (connected to a data table).

That makes sense if the array is repeatedly initialized...

When I initialize in the same case frame - but for the boolean "true",

then no values are recorded at all ... maybe autoindexing is missing?

Christian

[MikeS81]

Hi Christian,

you should also use the left part of the shiftregister, because there are your "old" values. See the attached picture.

Mike

[crickert]

Hi! 🙂

Still, only the last value is correct..

I noticed, that the tunnel on the right hand side is white inside -

unlike the one on the left hand side (see attachment).

Is this important?

[MikeS81]

Hi Christian,

it's still wrong in your image. Initialize the array in the true case (=0) and directly wire the left part of the shiftregister to the open tunnel on the right side of the case structure. If you really do this, then you don't have a dot on the tunnel of the right side.

Mike