Winterthur, June 2018 – All measurement technicians are familiar with the situation: today, several colleagues need devices for various measurements with a few channels, and tomorrow you have to tackle a major measuring task with several channels. This dilemma can be neatly resolved with several synchronizable data loggers. This sounds fine, but how does it work in practice?
A traditional measuring system with multiple channels is typically the established solution for recurrent identical measurements. However, a high degree of flexibility is called for when dealing with same-time measurement tasks, some of which require many, and others few channels. You could certainly resolve this situation by buying several identical data acquisitions systems. However, the high costs of this solution scarcely justify its deployment for ocassional usage. Resorting to less expensive manufacturers brings the disadvantage of potentially more inaccurate measuring results, the need for users to familiarize themselves with the different operation philosophy, not to mention installing and getting used to manufacturer-specific software. By contrast, high quality hardware and software can be used for diverse tasks, efficiency is substantially increased and procurement costs saved. The basis for this is formed by smart individual devices, which can be combined as the situation demands.
Synchronization via Precision Time Protocol (PTP) as an efficient solution. When recording measurement signals it is essential that this is performed concurrently, otherwise results may be completely misinterpreted. In principle, synchronization can be performed in two ways. The traditional solution: a separate line with a system clock is run to each device, ensuring that the respective measured values (samples) are recorded at the same time. The other option is to equip the relevant devices with a precise clock and to synchronize it periodically.
The PTP to IEEE 1588-2008 standard (corresponds to PTP V2) defines a sophisticated procedure in which the clocks of local network components can be synchronized to achieve an accuracy in the region of sub-microseconds with no additional lines at all. If measured values are then time-stamped, a higher-level computer can consolidate the data of many devices and, thanks to the time stamp, represent them precisely in a temporal context.
