Using Internal and External Clock Signals with Multiple PXIe-5665 Devices

You can have one external clock or one PXIe-5653 internal clock connected in common with multiple PXIe-5665 devices.

After interconnecting multiple PXIe-5665 devices, complete the following steps to allow multiple PXIe-5603/5605 modules to share a common LO source.

  1. Launch NI Measurement & Automation Explorer (MAX).
  2. In the Configuration pane, expand the Devices and Interfaces tree to see the list of installed devices.
  3. Expand your chassis tree item.
    MAX lists all available devices under the chassis. Your device names may vary.
  4. In the NI 5603 or NI 5605 Configuration dialog box, use the drop-down LO listbox to specify the PXIe-5653 module that is connected to the PXIe-5603 or PXIe-5605 by coaxial cables.
  5. For all additional downconverter daisy-chained devices, in the NI 5603 or NI 5605 Configuration dialog box, select External from the drop-down LO listbox.
  6. To set up either an external clock or an internal clock, complete the following steps. Notice that the internal clock source, if used, is the master PXIe-5665 (the first PXIe-5665 in the daisy chain).
    1. For each PXIe-5665 in the daisy chain except the last device, export the Reference Clock to the CLK OUT terminal using the niRFSA Export Signal VI or the niRFSA_ExportSignal function.
    2. For each PXIe-5665 in the daisy chain except the last device, specify that the LO source is exported by setting the LO Export Enabled property or the NIRFSA_ATTR_LO_EXPORT_ENABLED attribute to TRUE.
    3. For each PXIe-5665 in the daisy chain except the first device, use the niRFSA Configure Ref Clock VI or the niRFSA_ConfigureRefClock function to configure the Reference Clock source. For an internal clock, specify the CLK IN terminal as the Reference Clock source and set the Reference Clock rate to 100 MHz.
    4. For an external clock, set the first PXIe-5665 to use REF IN as the Reference Clock source.