ni579x Repeat Host Driven Synchronization

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Updated2023-02-17
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Use this synchronization method in conjunction with ni579x FPGA Align on the FPGA to synchronize the FPGAs.

This synchronization method returns to a known synchronization state from a previous run. If the synchronization data in values are incorrect, the FPGAs are not synchronized. Synchronization data is also only valid for a given system configuration. If FlexRIO FPGA modules, FlexRIO adapter modules, chassis, or slot locations change then synchronization data may not be valid.

Inputs/Outputs

synchronization data in valid

A flag to use the values from a previous synchronization run (synchronization data in) to return the FPGAs to that synchronization state.

synchronization data in

The synchronization data from a previous synchronization run that can be used to return the FPGAs to that synchronization state.

error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Default value: No error

sync.cptr.period

The period, in clocks, of the Common Periodic Time Reference (CPTR). The CPTR period controls the rate at which synchronized signals are realized. This parameter is required, and you must specify a value for each target to be synchronized.

When using ni579x FPGA Align, the CPTR period must be the same as the Reference Clock period. The sync.cptr.period must be set to the ratio of the clock-driven logic (CDL) rate (that the Align node is in) to the sync.meas.Reference Clock rate. For example, the CPTR period must be 13 if you are using PXI_Clk10 for the Reference Clock, and the IO Module\Sample Clock for the CDL clock (130 MHz / 10 MHz). When using ni579x Host Align, this value is configurable. The maximum value is 63. The minimum value for sync.cptr.period must be large enough to ensure transmission across the sync.cptr.FPGA I/O line. Refer to the specifications for the FPGA I/O line that you choose. For example, if the FPGA I/O line has a maximum propagation delay of 50 ns, the minimum value is 7 (the period of the 130 MHz IO Module\Sample Clock is approximately 7.692 ns, so 7 clocks are required to exceed 50 ns). NI does not recommend changing the CPTR period on-the-fly. Alignment must be re-run if you change the CPTR period.