What are the specific configuration steps for dual-sensor PTP synchronization?

Ensuring that the two sensors maintain time consistency with microsecond-level accuracy is the major objective of dual-sensor PTP synchronization, which guaranties the comparability of the data gathered. Based on the industry standard (IEEE 1588 PTPv2), the following configuration tasks are broken down into five stages: network configuration, software parameter tuning, hardware preparation, master/slave role setting, verification, and maintenance.

 

I. Setting Up Hardware and Networks

Verify Hardware Support

Verify that the IEEE 1588 PTP v2 protocol is supported by the sensors and the switches or controllers that are linked to them.

In order to achieve sub-microsecond precision, it is highly recommended that hardware timestamping be enabled. The precision needed for high-precision dual-sensor comparison cannot be met by standard software timestamping, which only offers millisecond-level accuracy.

Optimization of Network Topology

The best way to minimize latency jitter is to connect both sensors directly to a gigabit industrial switch that offers PTP capabilities, eliminating multi-layer or cross-router switching.

Isolate Traffic: To prevent bandwidth consumption from other large data transmissions (such file transfers and video streams) that can result in PTP packet queuing delays, create a separate VLAN or physical network for PTP synchronization if at all possible.

 

II. Establish Master/Slave Roles: The Optimal Master Clock Algorithm (BMCA) is used by the PTP protocol to automatically choose a master clock. To guaranty stability, it is advised to manually set the master clock in dual-sensor fixed scenarios:

Choose the sensor that acts as the system reference, has a greater crystal oscillator accuracy, or has more steady performance as the master clock.

In the settings, set its priority (Priority1) to a higher value (for example, less than 128; the smaller the value, the greater the priority).

Choose Slave Clock: To guaranty that the other sensor always synchronizes with the master, designate it as the slave and set its Priority1 to a lower number (for example, above 128).

 

III. Key Parameter Configuration: Establish the following fundamental settings in the PTP configuration interface or configuration file for both sensors:

The parameter item

Suggested Setting Value

An explanation

Version of PTP

IEEE 1588-2008 (v2)

The most compatible version is currently the standard industrial version.

Mode of Transmission

Layer 2 and UDP

Layer 2 usually offers reduced latency, therefore make your decision based on network device support.

Interval of Sync
-3 (125 ms) or -4 (62.5 ms)

For high-frequency data capture, shorter values are advised; in typical situations, 1 second (logSyncInterval=0) is appropriate.

Declare the Interval

1 second (logAnnounceInterval=0).

It can be used for negotiations between master-slave states; it doesn't have to happen quickly.

Latency Mechanism: P2P or E2E (End-to-End). P2P can be chosen for more reliable latency provided the switch enables transparent clocking and the link is straightforward. E2E is appropriate for the majority of switch situations.

Domain Number: 0. Make sure both sensors are in the same domain; this is the default domain.

Turn on the hardware timestamp. Making ensuring it is enabled at the network card/chip level is the most important step.