If your drive is faulted and the 6K does not report back a drive fault with TAS or TASF there are a couple of possibile explanations. The 6K allows you to choose the level that it sees as a drive fault. This allows you to use drives that have active low or active high drive fault outputs. The drive fault level is set with the DRFLVL command: 1 denotes active high and 0 denotes low. Another possibility is that drive fault detection is not enabled. The 6K is sent with drive fault detection disabled. Drive fault detection is enabled with the DRFEN command: DRFEN0 disables the feature and DRFEN1 enables drive fault detection.