Charpy, Alexandre

Johansson, H\ue5kan T

L\uf6her, B.

Simon, H.

T\uf6rnqvist, Hans

Löher, B.

Charpy, A.

Johansson, H.

Törnqvist, H.

GSI Repository

The DAQ readout library vmelib ∗B. Lo¨her1,2, A. Charpy3, H. T. Johansson3, H. Simon2, H. T. To¨rnqvist1, the R3B collaboration , andFAIR@GSI division1Institut fu¨r Kernphysik, Technische Universita¨t Darmstadt, Darmstadt, Germany; 2GSI, Darmstadt, Germany;3Chalmers Univ. of Technology, Go¨teborg, SwedenIntroductionA wide variety of physics experiments depend on thecorrect initialization and a fast and safe readout of modularelectronics connected to data acquisition (DAQ) computersvia standardized data buses (e.g. VME, CAMAC, PCIe, orother). A unified and standalone library framework provid-ing the facilities needed to handle the initialization, moni-toring and readout tasks in a safe and easy way does not yetexist. Existing libraries are usually either bound to workwithin a certain DAQ environment, require changes in thecode leading to frequent recompilation, are unsafe to use ornot meant to be changed by the users at all. In this reportwe present VMELIB, a library to fill this gap by addressingthe points above.To be a viable option for inclusion in a new project, oreven for replacing the specialized readout code in existingapplications there are a number of requirements such a li-brary should fulfill: configuration via text files on top ofsane defaults; unified API, no dependence on environment;consistency checks (config and data); support standard andfast transfer modes as well as multi-event readout; providelogging and debugging facilities; allow command line di-agnostics; unit tests for code quality; emphasis on portabil-ity and documentation. The realisation of a few of them invmelib is discussed below.ImplementationThe lightweight library is written in pure ANSI C, andconsists of several components (see Fig. 1): The configcomponent reads and parses the configuration. The cratecomponent represents crates (i.e. a data bus) and acts asbasis for DAQ operation. Each crate contains modules con-nected to a common data bus. The module component rep-resents a generic module. It exposes the common func-tional elements, such as creation, initialisation, and readoutof a physical module, while hiding its specific implementa-tion details. The util module contains auxiliary methods forlogging, memory allocation and provides the vmelib APIthat is exported to the environment. The test module is acollection of automated offline test cases to ensure correct-ness of each vmelib component and to prevent regressions.Configuration is done using text files, which declare alist of crates and their contained modules in a tree-like fash-ion. A complete configuration file can be very simple, herecreating a new Crate object with ID 0 that contains two∗Work is supported by HIC for FAIR, GSI-TU Darmstadt cooperationPSP codes 1.2.2.4, 1.2.5.1.4, and the BMBF project 05P12RDFN8.Figure 1: Schematic overview of vmelib (on the right), in-teracting with a DAQ environment and hardware.modules with their respective bus addresses:CRATE("VME0", 0) { # Name and crate IDmulti event = true # Use multi-event readoutGSI TRIDI(0x02000000) {} # Type + addressCAEN V775(0x00010000) {common start = truetime range = 1200 ns} }Default configurations are part of vmelib and the reasonbehind crate configurations being concise.Vmelib provides the functionality to set the configura-tion and to read data from the modules, leaving data storageand other tasks to the environment. Therefore, the neces-sary interface to interact with vmelib using a single VMEcrate consists of only a few function calls:Crate *vmelib setup(LogCallback, char *cfg file);void crate readout prepare(Crate *crate);uint32 t crate readout(Crate *crate, void **mem);void vmelib shutdown(Crate *crate);The complete API consists of a few more functions to allowfine-grained control, where needed.Use casesVmelib has been used in a variety of experimental se-tups, both for testing and production. The main user is theR3B collaboration, which has used vmelib in experimentstogether with the MBS data acquisition starting from 2014at GSI and Riken. The HIγS facility at TUNL has usedvmelib successfully for their γ3 experiments. The flexibil-ity of vmelib allowing for quick changes of module param-eters has been particularly appreciated in test setups.MU-NUSTAR-NR-08 GSI SCIENTIFIC REPORT 2014192 DOI:10.15120/GR-2015-1-MU-NUSTAR-NR-08

The DAQ readout library vmelib

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