VME Readout at and Below the Conversion Time Limit
Journal article, 2019

The achievable acquisition rates of modern triggered nuclear physics experiments are heavily dependent on the readout software, in addition to the limits given by the utilized hardware. This paper presents an asynchronous readout scheme that significantly improves the livetime of an otherwise synchronous triggered Versa Module Eurocard Bus-based data acquisition system. A detailed performance analysis of this and other readout schemes, in terms of the basic data transfer operations, is described. The performance of the newly developed scheme as well as synchronous schemes on two systems has been measured. The measurements show excellent agreement with the detailed description. For the second system, which previously used a synchronous readout, the deadtime ratio is at a 20-kHz trigger request frequency reduced by 30% compared to the nearest contender, allowing 10% more events to be recorded in the same time. The interaction between the network and readout tasks for single-core processors is also investigated. A livetime ratio loss of a few percents can be observed, depending on the size of the data chunks given to the operating system kernel for network transfer. With appropriately chosen chunk size, the effect can be mitigated.



Versa Module Eurocard Bus (VME)



nuclear physics


data acquisition


performance evaluation


M. Munch

Aarhus University

J. H. Jensen

Aarhus University

B. Loeher

Technische Universität Darmstadt


H. Toernqvist


Technische Universität Darmstadt

Håkan T Johansson

Chalmers, Physics, Subatomic and Plasma Physics

IEEE Transactions on Nuclear Science

0018-9499 (ISSN)

Vol. 66 2 575-584

Subject Categories

Computer Engineering

Communication Systems

Computer Systems



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