How many bytes may I read in ???

[Kristof Poppe]

I'm experimenting with the GPIB interface and a Fluke 45 dual display
multimeter.
But in the deliverd samplecode a number of bytes is read. How do I know
how many bytes I may read after a command. Is a big number alwys enough
and does this big number affect the speed of getting data ??

Any hint is welcome !

Thanx !

Kristof

[Albert.Geven]

the number is not critical. We normally ask for 256 characters and that does affect the speed not much. Most instruments are much slower than the pc !
It is wise to read enough characters and maybe it is slightly faster to stay within 32 characters.
These 32 character limit is only to prevent a new buffer to be setup for the gpib transfer. This happened in former years. I did not check this for visA2.5

[jwf]

The gpib program is going to read until it a.) times out; b.) reads the specified number of bytes; or c.) reads a termination character. That is why you put a large number of bytes to read, so it reads what is available. Putting to many bytes to read will not effect the speed.