mesytec-mvlc is a driver and utility library for the Mesytec MVLC VME controller written in C++. The library consists of low-level code for accessing MVLCs over USB or Ethernet and higher-level communication logic for reading and writing internal MVLC registers and accessing VME modules. Additionally the basic blocks needed to build high-performance MVLC based DAQ readout systems are provided:

• Configuration holding the setup and readout information for a single VME crate containing multiple VME modules.

  JSON and YAML formats are currently implemented.

• Multithreaded readout worker and listfile writer using fast data compression (LZ4 or ZIP deflate).

• Readout parser which is able to handle potential ethernet packet loss.

• Live access to readout data on a best effort basis. Sniffing at the data stream does not block or slow down the readout.

• Examples showing how to combine the above parts into a working readout system and how to replay data from a previously recorded listfile.

• Various counters for monitoring the system.

mesytec-mvlc is used in the mvme DAQ software.

• MVLC command format

• MVLC data format

• The readout_parser module

• mvme manual

  The mvme manual contains a section about the MVLC Trigger/IO system. mvme VME scripts supports all implemented MVLC commands.

apt-get update && apt-get install -y --no-install-recommends \
  ca-certificates build-essential git cmake ninja-build zlib1g-dev \
  libzmq3-dev

mkdir build && cd build
cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=~/local/mesytec-mvlc .. \
cmake --build . --target all
ctest .

Dockerfiles can be found here.

Pass -DMVLC_BUILD_DEV_TOOLS=ON -DMVLC_BUILD_TOOLS=ON to cmake to build additional tools.

• mvlc-cli: command line interface to the MVLC. Useful subcommands:

  • scanbus: Scans the upper 16 bits of the VME address space for (mesytec) VME modules.
  • register_read/register_write: Internal register access.
  • vme_read/vme_write: Single cycle VME access.
  • stack_info: Print readout command stack and trigger information.
  • show_usb_devices: Info about MVLC USB devices found on the system.

  mvlc-cli -h -a shows help for all implemented commands.

• mvlc-mini-daq: Standalone minimal DAQ tool. Configuration via .yaml/json files exported from mvme. Writes readout data to listfile and/or dumps it to console.

• mvlc-listfile-info <zipfile>: Processes the input listfile, showing information about the contained configuration and decoded readout/system events. Quick as it does not process the actual readout data.

• decode-mvlc-frame-header: reads raw frame headers from stdin, attempts to decode and print information:

   $ ./decode-mvlc-frame-header 0xf380001f
   0xf380001f -> StackResultFrame (len=31, stackNum=0, ctrlId=0, frameFlags=continue)
  

• decode-mvlc-eth-headers <header0> <header1>: decodes the ETH frame header words:

  ./decode-mvlc-eth-headers 0x00070004 0x00010000
  header0 = 0x00070004, header1 = 0x00010000
  header0: packetChannel=0, packetNumber=7, controllerId=0, dataWordCount=4
  header1: udpTimestamp=16, nextHeaderPointer=0x0000, isHeaderPointerPresent=1