Time synchronization

The rc_visard provides timestamps with all images and messages. To compare these with the time on the application host, the time needs to be properly synchronized. This can be done either via the Networt Time Protocol (NTP), which is the default, or the Precision Time Protocol (PTP).

Note

The rc_visard does not have a backup battery for its real time clock and hence does not retain time across power cycles. The system time starts in the year 2000 at power up and is then automatically set via NTP if a server can be found.

The current system time as well as NTP and PTP status can be queried via REST API and seen on the Web GUI’s System tab.

Note

Depending on the reachability of NTP servers or PTP masters it might take up to several minutes until the time is synchronized.

NTP

The Network Time Protocol (NTP) is a TCP/IP protocol for synchronizing time over a network. A client periodically requests the current time from a server, and uses it to set and correct its own clock.

By default the rc_visard tries to reach NTP servers from the NTP Pool Project, which will work if the rc_visard has access to the internet.

If the rc_visard is configured for DHCP (which is the default setting), it will also request NTP servers from the DHCP server and try to use those.

PTP

The Precision Time Protocol (PTP, also known as IEEE1588) is a protocol which offers more precise and robust clock synchronization than with NTP.

The rc_visard can be configured to act as a PTP slave via the standard GigE Vision 2.0/GenICam interface using the GevIEEE1588 parameter.

At least one PTP master providing time has to be running in the network. On Linux the respective command for starting a PTP master on ethernet port eth0 is, e.g., sudo ptpd --masteronly --foreground -i eth0.

While the rc_visard is synchronized with a PTP master (rc_visard in PTP status SLAVE), the NTP synchronization is paused.