A problem about property node

[hengfo]

Hi,

    Why this VI use property node before visa read?

[albertm]

Hi,

The 'Bytes at Port' property is read so that VISA Read knows how many bytes to get.

Albert

[hengfo]

Thank you, Albert.

Is property node absolutely necessarily? Visa read can get bytes itself. Are there many differences?

[tbd]

Hi hengfo,

      It's not necessary to use "bytes at port", in fact, I don't trust it, it seems there can be some strange latency! (see threads below)

Just go ahead and wire the number of bytes you want to read to the Read  - but be ready for a timeout error if the bytes you request don't arrive within the VISA timeout period.

See these threads:

http://forums.ni.com/ni/board/message?board.id=140&message.id=7839&requireLogin=False

http://forums.ni.com/ni/board/message?board.id=170&message.id=111079&requireLogin=False

[hengfo]

Thank you very much, tbd!