Device And Rtsi Clocks; Synchronizing Multiple Devices - National Instruments 6711 User Manual

In NI-DAQmx, some additional timing signals not shown in the figures can
Note
be routed to RTSI indirectly. Click the Device Routes tab in Measurement &
Automation Explorer for more information.

Device and RTSI Clocks

Many AO Series device functions require a frequency timebase to generate the necessary timing
signals for controlling DAC updates or general-purpose signals at the I/O connector. This
timebase is also called the Master Timebase or Onboard Clock. For more information, refer to
Master Timebase Signal
the
The AO Series device can use either its internal 20MHzTimebase signal or a timebase received
over the RTSI bus. The timebase can only be routed to or received from RTSI 7, or the RTSI
clock. The device uses this clock source, whether local or from the RTSI bus, as the primary
frequency source. If you configure the device to use the internal timebase, you also can program
the device to drive its internal timebase over the RTSI bus to another device that is programmed
to receive this timebase signal. The default configuration is to use the internal 20MHzTimebase
signal without driving the timebase onto the RTSI bus.
(NI DAQCard-6715 only)
only directly use its own internal 20 MHz timebase as the primary frequency source.

Synchronizing Multiple Devices

With the RTSI bus and the routing capabilities of the DAQ-STC, there are several ways to
synchronize multiple devices depending on your application. NI recommends that you use a
common timebase as the MasterTimebase signal and share any common triggers in the
application. One device is designated as the master device and all other devices are designated
as slave devices.
The 20MHzTimebase on the master device is the MasterTimebase signal for all devices. The
slave devices pull this signal from the master device across the RTSI trigger 7 line. Slave devices
also pull any shared triggers across an available RTSI trigger line from the master device. When
you start all of the slave devices before starting the master device, you have successfully
synchronized your application across multiple devices.
section of Chapter 3,
The NI DAQCard-6715 does not interface to the RTSI bus. It can
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Analog Output.
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