In reply to chr_sue:
Hi chr_sue, thank you for your answer,
1 - I can assure the timing from the waveform by seeing the data receiving state of the DUT is active when I try to send data, also the inout port data_bus is driven HZ by the DUT at this time.
2 - I place an info macro following line after the “example_vif.LA_EN <= 1’b1;”. According to the info prompt in the transcript, the case item is reached and the LA_EN has taken its value (HIGH). The odd part is here. I can see from the info prompt that the LA_EN has taken its value high, however it is still low at that time in the waveform as appears.
As I am sure that the case item is reached, knowing that it works if I drive the port outside the case statement, what would be wrong?
I would like to add that I drive other ports in the other case items like resetting the DUT and these ports working precisely.