Why does my Drive Fault output not work on my 615n

The Apex 615n has a sinking output labeled Fault Out on the Drive Auxiliary Connector. The manual states that any fault will turn this output off or cause it to float. If there is no fault then the output should be pulled to ground. This is true but the output will also float if the drive is disabled with the DRIVE0 command. So before checking to see if the input is indeed being pulled to ground ensure that the drive is enabled with the DRIVE1 command.