Synchronizing NI 446X Devices or NI 447X Devices at Different Sampling Rates

The following constraints apply when synchronizing only NI 446X devices at different sampling rates or only NI 447X devices at different sampling rates and using sample clock timebase synchronization:

• The ratio between sampling rates on all devices must be a power of two.
• NI 447X devices must use a sampling rate greater than 25.6 kS/s.

There are no constraints for multirate applications when using reference clock synchronization on supported devices.

The following are programming caveats to use when synchronizing only NI 446X devices at different sampling rates or only NI 447X devices at different sampling rates:

• When using sample clock timebase synchronization, account for differences in expected Sample Clock Timebase frequencies. First, read the SampClk.Timebase.Rate attribute/property from the master device. Then write this value to the SampClk.Timebase.Rate attribute/property on each slave.
• Regardless of synchronization method, ensure the master device allows the Sync Pulse sufficient time to reset all ADCs and DACs in the system. To guarantee adequate sync time, read the SyncPulse.SyncTime attribute/property from all slave devices. Then write the maximum of these values to the SyncPulse.MinDelayToStart attribute/property on the master before committing the master task.
• Regardless of synchronization method, you must account for filter delay between the devices.