How to optimise time synchronisation in manufacturing

Here, we examine the needs of manufacturing sites and consider how to optimise time synchronisation in manufacturing.

Manufacturing has specific needs when it comes to time synchronisation

In manufacturing, systems are often based on a sequence of synchronised events. This requires accurate timestamping by all machines involved in the task.

In a factory or on a production line, three types of system are available in general:

• Some production lines require more-or-less accurate synchronisation between machines, for example when filling containers with liquids. Or when fine timestamping is required, for instance when time-tagging events like zero-crossing detection
• Inspection and monitoring systems like Supervisory Control and Data Acquisition (SCADA) collect, aggregate and return all data on factory operations. For a clear view, it is vital to have the most reliable time-distribution service possible
• A factory’s overall centralised control system uses a primary reference clock to ensure all operations are carried out at the right time and are traceable. These include areas like production planning and flow management

In addition, as in all organisations, manufacturing sites need to synchronise daily operations ranging from telecommunications to access control.

Which time-synchronisation protocol is right for you and what must you consider?

Industry has evolved substantially, moving from mechanical to electromechanical to electronic systems. The future is leaning towards production robots transferring information to the cloud, towards the use of drones to inspect hardware, and of smart grids.

To choose your ideal time-synchronisation protocol, you must consider:

• Do you need relative or absolute synchronisation? In many cases, relative is sufficient. To achieve this, a time server acts as a reference clock and industrial devices synchronise with its time. If you need an absolute reference, you would generally use a clock with a GPS source
• Do you need synchronisation via wireless network or wired ethernet network? Wireless networks are sensor networks which timestamp events to communicate them to a SCADA system. These sensors rarely have internal clocks, and their energy connection and management dynamics require the use of specialised protocols. Synchronisation on a wired IP network is defined more clearly and the protocols for achieving it – like NTP – are well known.
• Is your time server reliable? Many industrial systems need time servers that are constantly available. Some protocols offer mechanisms to improve fault tolerance, and alternative reference clocks to cut switchover times. Other protocols separate the sending of synchronisation and data frames to reduce switchover times between clocks

How do you choose a time server?

Precision Time Protocol (PTP) enables you to synchronise devices down to tens of nanoseconds. However, its implementation needs specific hardware which can restrict large-scale deployment. NTP is used for general purposes and is suitable for applications involving several systems or production units.

For more on Bodet Time’s solutions for manufacturing

We provide dedicated solutions for the manufacturing sector, to help you improve productivity and communication. For advice on how to choose and implement a time server, bell or clock system