faster data transfer on ethernet

[shridharjosh]

Hi friends,

I am using VISA to control instrument through ethernet tcp/ip protocol.
the application is written in VB6 with the help of  measurment studio controls

i need to read  large matrix data , element by element ,since the insrument has no feature of bulk transfer

it is taking too long time to read the entire matrix .

the thing i observed was there is a 100mSec Delay between Visa Write and Visa Read ,(Visa read responses back after 100msec)
 this i observed with the help of  NI 488.2 SPY.

(this problem was not observed when controlling without the Visa )

is there any explaination why this 100msec delay is coming for each read , which amounts to enormous time for 30,000 elemenst read.

shridhar

[JoshuaP · Accepted solution]

Most of the defaults for VISA are set to optimize for large bulk transfers, since that is the norm for TCP/IP instruments. If you are transferring small amounts of data at a time there are several properties/attributes that you can change to get much better performance. Open up the VISA Help and take a look at the following attributes:

VI_ATTR_SUPPRESS_END_EN
VI_ATTR_TCPIP_NODELAY
VI_ATTR_TERMCHAR

More than likely you will just need to change the first two, because your instrument probably does not support any type of termination character.

-Josh