Precision Time Protocol (PTP)

Precision Time Protocol (PTP)


PTP is used in a computer network to synchronise clocks across that network. On a Local Area Network, this is sub-microsecond accuracy and is therefore suitable for timing, measurement and control systems.

PTP has very wide usage and the concept can be seen in diverse applications, such as mobile telephone networks and sub-sea acoustic arrays (navigation, survey, etc).

The official designation for PTP is IEEE1588, described as a packet-based two-way communications protocol specifically designed to synchronise distributed clocks with microsecond precision.

PTP for Industrial Camera Trigger Syncronisation

The Conveyor Belt Scenario

Industrial cameras differ from other imaging devices in that they are usually equipped with an IO port for direct camera control and for an external trigger source function. A single camera that is required to trigger when a light gate is opened (for example) will use an external trigger, such as fast moving goods on a conveyor. As the goods move further along the line, other cameras can be triggered in a similar manner at the appropriate time to validate a certain status. Syncronised triggering is obviously not required in this scenario.

The Multi-Camera Scenario

Some applications may require many cameras to acquire an image on a synchronised basis. In the past, this would have been achieved using a synchronised trigger signal to all the cameras. For this, a dedicated trigger conductor has to be connected to each camera from the trigger source.

PTP negates the need to use a dedicated external trigger. Instead, one of the cameras on the network can provide the function of a PTP Master - this camera receives the external trigger and in turn, will send a sync message via multicast messaging to the other cameras on the machine vision network.

Creating a PTP Industrial Camera Trigger System

To use PTP in your industrial camera network, the camera should be GigE 2.0 compliant. The network interface card should be IEEE1588 compatible.

PTP is not available with USB industrial camera products.

All GigE cameras supplied by Scorpion Vision are GigE 2.0 compatible and therefore have PTP functionality. Please don't hesitate to contact us if you wish to discuss a PTP network trigger requirement.



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