Is the PXI Express Chassis Accuracy Inherited To Peripherals?

Updated Oct 5, 2024

Reported In

Hardware

  • PXI Chassis

Issue Details

Does the PXIe chassis clock accuracy specification stack with the peripheral's clock accuracy specification, or does the peripheral's clock accuracy specification account for both?

For example, if the chassis clock accuracy is +/- 20 ppm, and the Time Board clock accuracy, derived from the PXIe clock is 100 ppm, is the Board's clock accuracy +/- 100 ppm or +/- 120 ppm?
 

Solution

 The clock accuracy describes how well the actual frequency matches the specified frequency. 

In this case, the reference clock accuracy of the board remains at +/- 100 ppm. The clock received from the chassis has an accuracy of +/- 20 ppm. However, after passing through board internal logic, the measured results yield a specification accuracy of +/- 100 ppm.

It is advised to base clock accuracy specifications on the specific module or peripheral device's specifications. While knowing the accuracy specification from the chassis is useful for exporting the clock to another chassis for synchronization, the internally generated clocking chip within the board has lower accuracy than the chassis reference clock.

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