hold the value of the output of the VISA read,

[betandwin]

Currently I make a vi file to read values from the serial port
VISA read will get periodic input from the serial port, and featured in a string constant.
I want if the input to the VISA read the same as before the string constants are not updated.
and still display data continuously.

I try to keep the value read by VISA read into a spreadsheet file, it's just the same result ..
every time there is no output from the VISA read, the indicator will lose value ..

in other words, holding the value of the output read visa.

I simulate with proteus serial data transmission. I include attachment

how can I do that?
thanks b4 ..

[MCOTO]

Hi,

The reason is that you are reading constantly using a while loop (without a timing VI by the way). You may read the buffer just when it is not empty. You can use a Case Structure and the property node in order to determine when to read the channel. Also, you may add a Wait Until next ms Multiple.vi in the while loop.

Regards,

MCOTO

[betandwin]

thank you for replying me ..
I have been waiting for days
I am a newbie ..
I dn't know about the property node ..
could you give more practical guidance?

An example might be,

[Albert.Geven]

Hi

In the serial palet you can find (very deep) "bytes at serial port"

type this in the search function of the labview palette and it will show and you can select it.

[MCOTO]

In this link you will find more information about this specific property node.

http://zone.ni.com/reference/en-XX/help/371361H-01/lvinstio/visa_bytes_at_serial_port/

You can find this property node where Albert mentioned in the last interaction.

Now just try to use a case structure in order to define the condition when to read.