Hi George, We discussed some solutions to solve the race you found. Since we want to avoid future requests and compatibility problems regarding the SRQ and Status Byte, we will fix the current ioctl. Furthermore we add two ioctls which return the original status message and avoid assumptions about the USB488 subclass definition. We will have the 3 STB ioctls: 1) USBTMC488_IOCTL_READ_STB always reads the STB from the device and if the associated file descriptor has the srq_asserted bit set it ors in the RQS bit to the returned STB and clears the srq_asserted bit. Comment: This ioctl will return the latest status byte again, but will not loose the RQS bit sent by intermediate SRQ messages. This ioctl should be conform with 488.2 devices. 2) USBTMC_IOCTL_GET_STB always reads the STB from the device and returns the STB unmodified to the application. The srq_asserted bit is not changed. 3) USBTMC_IOCTL_GET_SRQ_STB if the associated file descriptor has the srq_asserted bit set it returns the STB originally sent in the device SRQ message and clears the srq_asserted bit otherwise it returns error code ENOMSG. Please let us know your feedback and comments. Regards, Guido
