Linux

Warning

4.X versions of linuxptp which implement PTP version 2.1 (IEEE 1558-2019) will not properly sync with the MultiSense’s onboard PTP implementation.

The following line needs to be added to the /etc/linuxptp/ptp4l.conf file on the machine acting as a PTP master to resolve the compatability issues.

ptp_minor_version       0

  • Each interface which has MultiSense camera connected will need a stand-alone phc2sys service.

  • The following is an example phc2sys command we use for synchronizing cameras on a specific interface
    • phc2sys -c <interface> -S 1 -s CLOCK_REALTIME -l7 -O 0 -m

      • -c <interface> sets the sink clock to be the device <interface>, which is populated with the connected interfaces.

      • -S 1 indicates that the step threshold is 1 second, meaning that if the network interface’s clock lags the system clock by more than a second, then it will be adjusted via a discontinuous clock step (rather than increasing the frequency of the hardware clock to gradually catch up).

      • -s CLOCK_REALTIME sets the source clock to be the system’s realtime clock.

      • -l7 enables debug logging.

      • -O 0 indicates that the offset between the source and sink clocks is 0 seconds (meaning, they should be the same time).

      • -m enables printing to the standard output.

    • For each of the phc2sys instances, we need a corresponding ptp4l service running on the host system.
      • We run with the following configuration

        • ptp4l -q -f ptp4l.cfg

        • Here, -q disables logging to the system log

        • -f ptp4l.cfg loads the rest of the config for a specific interface.

        • Here is an example of a ptp4l.cfg file configured for the enp5s0 interface.

[global]
# Ensures that the interface can only set other clocks, and cannot have its clock set by the host machine.
masterOnly  1
# More logging.
verbose             1
# Debug logging.
logging_level       7
# Specifies the time-to-live limit for multicast messages, ensuring that they can hop at most 2 subnets.
# Update depending on your network topology
udp_ttl             2

# This line changes depending on the network interface.
[enp5s0]