PPS Signal Availability on the FPGA Through PTP for cRIO Controllers

Issue Details

I'm working with a CompactRIO (cRIO) controller that supports the Precision Time Protocol (PTP). The time synchronization between my systems through this protocol is working as expected. 

However, I would like to know whether it is possible to access the PTP Pulse‑Per‑Second (PPS) signal directly from the FPGA. Specifically, I want to determine if this PPS signal can be routed to the FPGA and then exported through a digital output channel for use by external hardware.
Is this functionality supported on cRIO platforms?

Solution

Time Sensitive Networking (TSN)-enabled cRIO controllers allow you to access some timing signals through the FPGA. The specific models are listed below:

• cRIO-9035 (Sync)
• cRIO-9039 (Sync)
• cRIO-904x 
• cRIO-905x

If you add one of these devices to a LabVIEW project, the following signals will be available under the FPGA target:

However, none of them correspond to a PPS signal that can be accessed from the FPGA nor routed to a digital output channel.

The available timing-related FPGA signals are described below:

• Time: Represents the current time in nanoseconds since an epoch (a fixed point in time from which elapsed time is measured).
• Time Source: Provides information about where the time is being sourced from. Possible options are:
  • None: The time is not synchronized.
  • System: The time is synchronized to the system time. 
  • External: The time is synchronized to the time reference external to the system. 

• Time Synchronization Fault: Boolean value that indicates if there is a synchronization error.
• Offset from Time Reference: Represents the offset in nanoseconds from the time reference. If the controller is not synchronized to the external source, this magnitude will be zero. 
• Offset from Time Reference Valid: This magnitude indicates whether the offset is reliable. For example, this parameter will be True if the Time Synchronization Fault signal is False.

If you require to generate a PPS signal on the FPGA, you can create one by using the Time signal mentioned above. As a guide, you can use the Time Sensitive Network (TSN) Community VIs Toolkit for LabVIEW available through the VI Package Manager. The toolkit includes a self-contained VI that generates a PPS output and exports it to a digital output channel.

Note: The Time Sensitive Network (TSN) Community VIs Toolkit for LabVIEW is a third-party product that is not directly supported by NI.