The scan clock or the update clock (depend on your operation) of the MIO device can be routed to the RTSI line by calling route signal.vi if you are using LabVIEW or select signal funcation call if you are using NIDAQ C functions. The digital device can then route the clock signal from the RTSI line to the REQ pin of the 6533 device (if you are doing a pattern i/o operation, if you are doing a burst mode operation, then that clock signal should be routed to the PCLK pin). Since the MIO device is providing the clock signal that is the master device, and the digital device is the slave device. The slave should start first and wait for the clock. If you want your digital device to output the clock, that can be done as well using the same idea, route the clock to the RTSI lines and route again the the scan clock or update clock. There is not any direct method to output the clock through one of the 32 digital lines, you can look at the clock signal directly from the i/o connector of the MIO device.