PTP Grandmaster Clock (TM2000B)

A Linux PC or Raspberry Pi running e.g. linuxptp can act as a software PTP master - and in our showcase this alone reduces the cross-device sync error by 99%+ (from 1-2 ms to below 10 µs). It is a good option for quick tests when a suitable Linux host is already at hand and someone can keep it running.

However, the software approach has practical limits: The PC clock itself is only as accurate as its NTP source, the host must stay powered and maintained 24/7, the PTP messages are typically timestamped in software (or depend on network card support) which adds jitter - and setup requires Linux know-how.

The TM2000B addresses this as a dedicated device: GPS-disciplined absolute time, PTP messages timestamped in hardware at the network port, OCXO holdover if GPS is lost - and a 2 minute browser-based setup with no host to maintain. We recommend it for test labs, end-of-line stations, vessels and any deployment that must run unattended, e.g. in the field.

Note that the CANsub itself hardware timestamps every CAN frame at 1 µs resolution regardless of the PTP master. The master only determines how precisely the device clocks are aligned to each other and to UTC.

1. Antenna: Place the GPS antenna with a clear view of the sky and connect it to the SMA port on the rear of the TM2000B. The antenna has a magnetic base and a 5 m cable, so it can be placed well away from the unit.

2. Power and network: Connect the included 12 V power supply and an Ethernet cable from the TM2000B to your switch or router. The unit boots within seconds and the POW LED turns on. Optionally, you can use a Power-over-Ethernet adapter to power the TM2000B for easier installation (not included).

3. Configure: Open the web interface in your browser (default IP 192.168.1.20 - or enable DHCP) and set your network and PTP settings. For multiple CANsub devices, use multicast mode.

4. GPS lock: Wait for the LOCK LED to turn solid (3D GPS fix) and the SEC LED to blink once per second - the TM2000B is now serving GPS time as PTP grandmaster on your network. A first fix typically takes less than a minute with a clear view of the sky.

5. CANsub: No configuration is needed on the CANsub. With a PTP grandmaster present on the network, the devices sync to it automatically - whether you use webCAN, python-can, SavvyCAN or your own apps.

See the quick setup guide and product manual for details.

The TM2000B is manufactured by a 3rd party (TimeMachines). We have selected and tested it as a low cost, easy-to-deploy PTP grandmaster for the CANsub and offer it as an accessory for CANsub users who need multi-device time synchronization.

We are happy to support questions related to using the TM2000B with the CANsub - incl. via our showcases and guides. For technical questions beyond the TM2000B + CANsub, we refer to the TimeMachines documentation and their support.

Yes. In our CAN via Ethernet article, an office Linux PC running a software PTP master brings 2 x CANsub.4 to within 10 µs of each other - a good option for quick tests when a suitable host is available. The TM2000B is the professional-grade alternative: It adds GPS-disciplined absolute time, PTP messages timestamped in hardware at the network port (rather than in software), holdover if GPS is lost and a 2 minute setup - with no PC to keep running. In our own test with the TM2000B, the two CANsub.4 devices synced to within about +/- 1 µs of each other - and to absolute UTC.

Either way, the CANsub hardware timestamps every CAN frame at 1 µs resolution - with or without a PTP master. The master only determines how precisely the device clocks are aligned to each other and to UTC.

No. The CANsub syncs to a PTP grandmaster on its network automatically - there are no settings to change on the device. Since the clock alignment happens on the CANsub itself, it applies across all the CANsub software tools, incl. webCAN, python-can, SavvyCAN and your own REST/WebSocket apps. The CANsub also exposes its PTP sync status, as shown in our showcase dashboard.

Not necessarily. The included active patch antenna (5 m cable, magnetic base) typically achieves a 3D GPS lock when placed on a window sill or another spot with a reasonable view of the sky. In metal buildings, below deck on a vessel or in shielded test halls, an outdoor antenna is the robust solution: TimeMachines offers outdoor antenna kits with mounts, lightning arrestors and up to 250 ft of cable - see the outdoor antenna guide.

No. The TM2000B gets the time directly from the GPS satellites and distributes it on your local network. This means it works on networks with no internet access at all, e.g. an isolated test lab network or a ship - and the time does not depend on an internet time server. Besides PTP for your CANsub devices, it can also serve NTP to the PCs and servers on the same network.

Each CANsub timestamps every RX/TX CAN frame at 1 µs resolution 'at the edge'. Without PTP, each device runs on its own clock, and clocks drift apart - typically by tens of milliseconds over a day. With PTP against the TM2000B, all CANsub devices stay within 10 µs of each other and of UTC. For reference, a single CAN frame at 500 kbit/s takes 200+ µs on the bus - so the order and relative timing of frames across devices becomes unambiguous.