National Instruments 6711 User Manual

Also see for DAQCard-6715: User manual User manual

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National Instruments 6711 User Manual Manual pdf 61 page image

© National Instruments | 8-3TitleShort-Hidden (cross reference text)Note In NI-DAQmx, some additional timing signals not shown in the figures canbe routed to RTSI indirectly. Click the Device Routes tab in Measurement &Automation Explorer for more information.Device and RTSI ClocksMany AO Series device functions require a frequency timebase to generate the necessary timingsignals for controlling DAC updates or general-purpose signals at the I/O connector. Thistimebase is also called the Master Timebase or Onboard Clock. For more information, refer tothe Master Timebase Signal section of Chapter 3, Analog Output.The AO Series device can use either its internal 20MHzTimebase signal or a timebase receivedover the RTSI bus. The timebase can only be routed to or received from RTSI 7, or the RTSIclock. The device uses this clock source, whether local or from the RTSI bus, as the primaryfrequency source. If you configure the device to use the internal timebase, you also can programthe device to drive its internal timebase over the RTSI bus to another device that is programmedto receive this timebase signal. The default configuration is to use the internal 20MHzTimebasesignal without driving the timebase onto the RTSI bus.(NI DAQCard-6715 only) The NI DAQCard-6715 does not interface to the RTSI bus. It canonly directly use its own internal 20 MHz timebase as the primary frequency source.Synchronizing Multiple DevicesWith the RTSI bus and the routing capabilities of the DAQ-STC, there are several ways tosynchronize multiple devices depending on your application. NI recommends that you use acommon timebase as the MasterTimebase signal and share any common triggers in theapplication. One device is designated as the master device and all other devices are designatedas slave devices.The 20MHzTimebase on the master device is the MasterTimebase signal for all devices. Theslave devices pull this signal from the master device across the RTSI trigger 7 line. Slave devicesalso pull any shared triggers across an available RTSI trigger line from the master device. Whenyou start all of the slave devices before starting the master device, you have successfullysynchronized your application across multiple devices.