Neutron detectors based on solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option for neutron scattering instruments at the European Spallation Source ERIC that require excellent spatial resolution combined with time resolution, high-rate capabilities and a good neutron detection efficiency. The NMX macromolecular diffractometer will consist of three individual Gaseous Electron Multiplier (GEM) detectors mounted on robotic arms to allow positioning of the detectors in an optimal manner. The detectors will have an active area of about 50 x 50 cm² each, with a gadolinium cathode acting as neutron converter. They are designed to minimize the dead area within the detector volume as well as the space between the individual detectors when placed in close proximity to each other. Each NMX detector is designed to be a stand-alone device with all services (gas, powering, cooling, read-out electronics,…) attached to its case in a way such that the fully integrated system can be moved freely throughout operation.

The RD51 Collaboration has developed a multi-purpose and versatile readout system that can be scaled from a single laboratory detector to LHC-like experiments: The Scalable Readout System (SRS). Different frontend ASICs have been implemented in the SRS so far, with the APV25 as the current state-of-the-art chip used by many groups and for experiments upgrade R&D. There is a strong interest of many R&D and detector groups to use the VMM ASIC developed for the ATLAS New Small Wheel with the SRS for their applications. Within the BrightnESS project, the VMM is implemented in the SRS to read out the prototype GEM based neutron detector for the NMX instrument. New FPGA firmware, dedicated hardware and software is under development. A full-scale demonstrator detector was designed and is currently under construction to prove that GEM-based neutron detectors with state-of-the-art electronics meet the experimental requirements for high-flux thermal neutron detectors installed at the NMX instrument at ESS.

The current status of the developments, capabilities of the SRS based VMM read-out and latest results will be presented.