VHDL/GPIB IEEE488

Hello all,

I am an intermediate VHDL programmer and I have a project that requires 
me to use FPGAs for one portion of the project. The other portion of the 
project, I need to be able to send commands to Lab equipment via GPIB 
(IEEE 488.2) to measure signals from portion 1 of the project.

Through some digging, I have found timing diagrams of the the GPIB 
handshake protocols, however there are 8 data lines that I cannot find 
any info on. for example, if I want to to measure a signal, which data 
lines go high or low to accomplish this task?

There is a standard command library for C++ code to control GPIB, 
however I would like to avoid it if possible. Does anyone know of how I 
can do this? I searched for a IP core but I only found one and it was no 
longer supported.

Thanks!!!
Jonathan