MEDM

MEDM
Name	MEDM
Developer	Argonne National Laboratory; Los Alamos National Laboratory
Released	1990s
Programming language	C (programming language)
Operating system	Unix-like systems; Linux; SunOS
Genre	SCADA; control system operator interface
License	MIT License; permissive

MEDM MEDM is a graphical operator interface tool originally developed for use with the Experimental Physics and Industrial Control System (EPICS) toolkit. It provides a windowed, widget-based environment for designing and running control screens for particle accelerators, synchrotrons, fusion experiments, and other large scientific instrument installations. MEDM became a common choice among facilities that adopted EPICS alongside tools and institutions such as Los Alamos National Laboratory, Argonne National Laboratory, and the European Organization for Nuclear Research.

Overview

MEDM presents collections of graphical widgets—meters, buttons, sliders, and text fields—mapped to EPICS process variables used in installations like the Stanford Linear Accelerator Center and the Thomas Jefferson National Accelerator Facility. It interoperates with EPICS Channel Access and integrates with device I/O layers developed at places including Oak Ridge National Laboratory and Brookhaven National Laboratory. Operators at facilities such as Lawrence Berkeley National Laboratory and Fermi National Accelerator Laboratory have historically used MEDM as part of human-machine interfaces alongside alternatives like Control System Studio and Extensible Display Manager.

History

MEDM emerged in the 1990s during EPICS’ expansion across accelerator and laboratory projects such as the Spallation Neutron Source and the Advanced Photon Source. Early contributors were staff from Los Alamos National Laboratory and Argonne National Laboratory, building on X Window System toolkits and the Motif widget set common in that era. As EPICS evolved through versions and as institutions like SLAC National Accelerator Laboratory and CERN explored control-room ergonomics, MEDM was adapted to support evolving Channel Access semantics and display requirements. Over time, maintainers in the EPICS community and site-specific teams added features and ported MEDM to modern Unix-like systems and legacy platforms such as SunOS.

Architecture and Features

MEDM is implemented in C (programming language) and uses the X Window System and Motif libraries for rendering. Its architecture centers on a display file format describing widget hierarchies, graphical attributes, alarm thresholds, and process variable bindings applicable to installations like Diamond Light Source or ISIS neutron source. Important features include real-time variable updates via EPICS Channel Access, alarm colorization tied to EPICS alarm severities, and configurable action scripts triggered by operator interactions. MEDM supports bitmap and vector graphics, text annotations, and grouping of widgets to mirror control layouts used at facilities such as DESY and TRIUMF.

Usage and Applications

Operators use MEDM to monitor and control systems in contexts including particle accelerators, synchrotron beamlines, tokamaks, and industrial testbeds. Representative deployments include beamline control panels at European Synchrotron Radiation Facility, cryogenic system interfaces at CERN, and magnet power-supply consoles at Brookhaven National Laboratory. MEDM screens are commonly incorporated into control-room workflows with software such as EPICS Archiver Appliance, pvAccess, and sequencing tools developed at Oak Ridge National Laboratory. Training programs at institutions like Lawrence Livermore National Laboratory and Argonne National Laboratory have historically included MEDM for operator certification on legacy EPICS stacks.

File Formats and Configuration

MEDM uses a plain-text display file format that encodes widget types, positions, colors, fonts, and EPICS process variable links—similar in spirit to other EPICS display managers used at SLAC National Accelerator Laboratory and Fermi National Accelerator Laboratory. Configuration typically includes resource files and environment variables used to locate Channel Access hosts and font resources on systems like Linux or SunOS. Display files created at sites such as Los Alamos National Laboratory can be version-controlled alongside control-system databases maintained with tools from Argonne National Laboratory or Brookhaven National Laboratory.

Integration and Compatibility

MEDM integrates with EPICS Channel Access and coexists with other EPICS ecosystem components including Input/Output Controller, EPICS Base, and data archivers developed by teams at Oak Ridge National Laboratory and SLAC National Accelerator Laboratory. Though MEDM predates modern web-based GUIs such as Control System Studio and Phoebus, it remains compatible with PV naming conventions and alarm handling used across many legacy control rooms at facilities like Diamond Light Source and ISIS neutron source. Community ports and builds have targeted modern Linux distributions and X11 toolchains maintained by projects at institutions including CERN and Lawrence Berkeley National Laboratory.

Development and Community

MEDM’s development has been sustained by the dispersed EPICS community, with contributions and site-specific forks originating from Los Alamos National Laboratory, Argonne National Laboratory, and various university and national-laboratory control groups. Mailing lists, code repositories, and collaborative forums maintained by the EPICS collaboration link MEDM users from Fermi National Accelerator Laboratory, SLAC National Accelerator Laboratory, and Brookhaven National Laboratory. While newer tools receive active feature development at organizations like Diamond Light Source and European Organization for Nuclear Research, MEDM retains a user base maintaining displays, migration tools, and documentation within the EPICS ecosystem.

Category:EPICS Category:Control system software