How can I read without EOI line assert?

[dongil]

Hi.

Our machine used ibrd() for read from Tester(another machine).
but i don't read data from Tester now.
Tester used Send(....,NULLend)function of GPIB 488.2.
I know that NULLend is not assert EOI line and don't send new line character.
But Tester's program can't change source code.

our machine Tester
Send(....NULLend)
* ibrd <-
* (don't read)
* (time out)
* ibrd
* (read data)

I want read data from tester without changed Tester's program.

Any advice????

[DiegoF]

Hi,

You shouldn't have any problems reading from a device that does not assert the EOI line or sends a termination character. When you do a ibrd, the function will wait for the specified timeout period and return with a timeout error and the accepted bytes.

You'll have to set the timeout value so that you give enough time to the device to transfer all the data. For example, if you do an ibrd for 100 bytes, the timeout is set to 1 second and the instrument send 50 bytes. The ibrd function will return one second later with the 50 received bytes. If the device sends more that 100 bytes, the ibrd function will return inmediatly. You'll probably have to call ibrd again until it times out, since that would be the only garantee that the device send all the da
ta.

Hope this helps.

DiegoF.
National Instruments.